~yasui ～やすい, 安い, 易い

In Japanese, ~yasui ～やすい is an auxiliary adjective that means something is "easy" to do or to happen. It's also a normal i-adjective that means "easy," yasui 易い. When the word is written with a different kanji, yasui 安い, it means something is "cheap" or "calm."

Auxiliary Adjective

Usage

The auxiliary adjective ~yasui ～やすい is used after the masu stem of a verb, also called the "connective form," ren'youkei 連用形. For example:

suru
する
To do.
shimasu
します
To do. (polite form.)
shi
し
Doing. (noun.)
shi-yasui
しやすい
Doing is easy.
Easy to do.

Since yasui is an auxiliary adjective, it turns the verb into an adjective. This means that nouns that would become objects in sentences (marked by wo を) can become subjects instead (marked by ga が). For example:

shigoto
仕事
Work. (noun.)
shigoto wo suru
仕事をする
To do the work. (the work is the object.)
shigoto ga suru
仕事がする
The work does. (this doesn't make sense.)
shigoto ga shi-yasui
仕事がしやすい
The work is easy to do. (predicative adjective.)
shiyasui shigoto
しやすい仕事
Work [that] is easy to do. (attributive adjective.)

Also, since it turns the verb into an adjective, the English translation may become a single adjective instead of a whole phrase. For example:

tokeru
溶ける
To dissolve.
toke-yasui
溶けやすい
Easy to dissolve.
That dissolves easily.
Soluble.

Conjugation

Since yasui is an i-adjective, it can be conjugated like one to mean something "was easy," "is not easy," "was not easy," and so on.

~yasui
～やすい
Easy [to do].
~yasukatta
～やすかった
Was easy [to do].
~yasukunai
～やすくない
Not easy [to do].
~yasukunakatta
～やすくなかった
Was not easy [to do].

See the Conjugation of i-Adjective for details.

Easy to Do vs. Easy to Happen

Literally, yasui やすい means "easy." But it can mean something, an action, is easy to do, or it can mean it's easy to happen. The latter ends up meaning something is likely to happen, that it has a tendency to happen, because things that are easy to happen tend to happen.

wasure-yasui
忘れやすい
Forgetting is easy to do.
Forgetting is easy to happen.
Forgetting tends to happen.
watashi wa wasure-yasui
私は忘れやすい
"As for me, forgetting is easy to do."
It's easy for me to forget things.
I tend to forget things.
tanjoubi wa wasure-yasui
誕生日は忘れやすい
"As for birthdays, forgetting is easy to do."
It's easy to forget birthdays.
People tend to forget birthdays.
kyoumi aru koto wa oboe-yasuku
kyoumi nai koto wa wasure-yasui
興味あることは覚えやすく
興味ないことは忘れやすい
[While] things [you] have interest are easy to remember,
things [you have] no interest are easy to forget.

There's no way to tell these two meanings aside from the context. But it's really not that hard to guess which is it. For example:

tabe-yasui
食べやすい
Eating is easy to do.
~~Eating is easy to happen.~~ (wrong!)

A hint is that transitive verbs tend to be easy to do, while intransitive verbs tend to be easy to happen.

This comes from the fact that when you're talking about a certain thing, a transitive verb implies your ability to do something with it: it's easy to do X with this, whereas an intransitive verb implies the how easy that verb can spontaneously happen: it's easy for X to do this.

kowasu
壊す
To break [something.] (transitive.)
kowareru
壊れる
To break. (intransitive.)
kowashi-yasui
壊しやすい
Easy to break [something].
This thing looks like I, or someone else, could break it easily.
koware-yasui
壊れやすい
Easy to break. (itself.)
This thing looks like it breaks easily, that is, it could break anytime now, for any reason. Totally unreliable!

易い

Besides being an auxiliary adjective, yasui やすい, or rather, yasui 易い, is also a normal i-adjective that means something is "easy."

anzuru yori umu ga yasushi
案ずるより産むが易し
anzuru yori umu ga yasui
案ずるより産むが易い
Compared to worrying, producing is easy.
Producing is easier than worrying.
- Idiom about not thinking too much about it and just... do it!

Note that yasui isn't normally used as a stand-alone adjective for "easy" like in the phrase above. It's normally used as an auxiliary adjective instead.

Tayasui たやすい【容易い】

The word tayasui たやすい, also written tayasui 容易い, means something is really "easy" "or "simple" to do. It's often used to mean something was done, or can be done, with more ease than one would imagine.

shisha wo yomigaeraseru nante tayasui koto
死者を蘇らせるなんて容易いこと
Something like reviving the deceased is a simple thing to do.
- It's a walk in the park.
- Anyone can do it.
- I could do it with my eyes closed.
tayasuku kaiketsu suru
容易く解決する
To solve it simply.
To solve it easily.
To solve it effortlessly, without any trouble.

Often, however, tayasui 容易い is used in its negative inflection to say something is not as easy as one would imagine.

tomodachi wo tsukuru no wa tayasui koto janai
友達を作るのはたやすいことじゃない
To make friends is not a simple thing to do.

Note that tayasui can be written with kanji as tayasui 容易い because it's an ateji 当て字. Specifically, 容 isn't normally read as ta. It seems that there was the word youi 容易, which also means "easy," and since tayasui matched the "easy" meaning it became written like that.

安い

When yasui is written as yasui 安い it doesn't mean "easy" but something else.

"Cheap"

Usually, yasui 安い means something is "cheap," either because it's on discount, or is a good deal, or because it's worthless, not as good as a well-made product.

yasui fuku
安い服
Cheap clothes.
yasukute kawaii fuku
安くて可愛い服
Cheap [and] cute clothes.
Clothes that are cheap and also cute.
yasuku katta
安く買った
Bought for cheap.
Bought cheaply.

It can also mean the cost of doing something was cheap, rather than the price of a product.

腕が！！！安いもんだ腕の一本くらい･･･無事でよかった･････････う･･････････････････！！うう･････････！！

Manga: One Piece (Chapter 1)

Context: Shanks sacrifices his arm to save Luffy. (this is literally the first chapter.)
ude ga!!!
腕が！！！
[Your] arm [is gone]!!!
- Implicit verb: we have the subject marker ga が explicit but the sentence has no explicit verb.
yasui mon da
安いもんだ
[It's a] cheap [price to pay]
- mon もん
  mono もの
  "Thing." This is a formal noun.
ude no ippon kurai...
腕の一本くらい･･･
[Something] as much as one arm...
- ippon 一本
  One cylindrical object. (e.g. one arm. This is a counter.)
buji de yokatta
無事でよかった
That [you] are unharmed was a good [outcome.]
[I'm glad you aren't hurt.]
.........u...
............!!
uu.........!!
･････････う･･･
･･･････････････！！
うう･････････！！
*sobbing piratically*

In this case, yasui is sometimes written as yasui 廉い instead.

"Calm"

The word yasui 安い can also mean something is "calm" or "quiet." This is in the same sense as anshin 安心 means "relief" or "peace of mind."

kokoroyasui
心安い
It's a relief.
(also refers to someone who's "carefree," "friendly.")

Apparently, it's from this "calm" meaning that the "cheap" meaning came from: something that's expensive makes people nervous, but something that's cheap is more calming.

安らか、安らかな

The word yasuraka 安らか, clearly related, means "tranquil" or "peaceful." It's a na-adjective, often taking the form of yasurakana 安らかな.

yasurakana nemuri
安らかな眠り
Peaceful sleep. Tranquil sleep.
yasurakana shi
安らかな死
Peaceful death.

Antonyms

Since yasui has multiple meanings, yasui has multiple antonyms too.

The antonym of the auxiliary adjective ~yasui would be:

~nikui
～にくい
Hard to do.

It works exactly the same way, for example:

shi-nikui
しにくい
Hard to do.
tabe-nikui
食べにくい
Hard to eat.
koware-nikui
壊れにくい
Hard to break. Unlikely to break.

For the normal adjective meanings, the antonyms would be:

muzukashii
難しい
Difficult. Hard.
takai
高い
Expensive.
- This word also means "high," which is the antonym of "low" instead.

"Easy" in Japanese

Although yasui 易い means "easy," "easy" doesn't always mean yasui. That is, some stuff we'd call "easy" in English aren't called yasui in Japanese.

Easy Game Difficulty

When talking about the "level of difficulty," nan'ido 難易度, of a game, Japanese games generally use the following words:

yasashii
易しい
Easy. (easy mode.)
futsuu
普通
Normal.
muzukashii
難しい
Difficult. (hard mode.)

Note: yasashii 優しい means "gentle," but when it's written as yasashii 易しい it means "easy" instead. Sometimes, this yasashii is written without kanji instead: yasashii やさしい.

Sometimes they use katakanizations or English words instead.

iijii
イージー
Easy.
noomaru
ノーマル
Normal.
haado
ハード
Hard.

Note that, when you play the easy mode of a game, it becomes:

kuria shi-yasui
クリアしやすい
Easy to clear.
- kuria suru
  クリアする
  To clear (a game.) To finish, complete, beat a game.
- In some games, finishing a stage gives you a "stage clear" message. So finishing the whole game gets you "game clear."

Easy Woman

Some idioms also don't match Japanese exactly. For example, an "easy woman" in English refers to sexually promiscuous woman, i.e. "easy to sleep with."^{[an easy man / an easy woman. - forum.wordreference.com, 2019-01-08]}

In Japanese, the term yasui onna 安い女 actually has the same meaning. However, because of how it's written, it literally means "cheap woman" rather than "easy woman," as in, it doesn't cost much to get. There's also terms like karui onna 軽い女, "light woman," i.e. loose woman, that one might translate as "easy woman" even though it's not literally the same thing.

Examples

For reference, some more examples:

yomi-yasui
読みやすい
Easy to read.
- yomu
  読む
  To read.
nomi-yasui
飲みやすい
Easy to drink. (e.g. pills.)
- nomu
  飲む
  To drink.
kawari-yasui
変わりやすい
Easy to change.
(e.g. fickle weather.)
- kawaru
  変わる
  To change. (intransitive.)
aki-yasui
飽きやすい
Easy to become bored with.
Easily bored.
- akiru
  飽きる
  To get bored of.
kanji-yasui
感じやすい
Easy to feel.
Sensitive. Susceptible. Impressionable.
- kanjiru
  感じる
  To feel.
kizutsuki-yasui
傷つきやすい
Easy to hurt.
- kizutsuku
  傷つく
  To hurt.
  To attach an injury. (literally.)
damasare-yasui
騙されやすい
Easy to be tricked.
Gullible. Naive.
- damasareru
  騙される
  To be fooled. To be tricked.
  (passive form of...)
- damasu
  騙す
  To fool. To trick.
tsukai-yasui
使いやすい
Easy to use.
- tsukau
  使う
  To use.
atsukai-yasui
扱いやすい
Easy to handle.
- atsukau
  扱う
  To handle.
tsukare-yasui
疲れやすい
Easy to get tired.
Gets tired easily.
- tsukareru
  疲れる
  To get tired.

分かりやすい

wakari-yasui
分かりやすい
Easy to understand.
- wakaru
  分かる
  To understand.
wakari-yasuku setsumei shite kudasai
分かりやすく説明してください
Please explain [it] [in a way that is] easy to understand.

Note: the phrase wakariyasui is sometimes used in anime to say someone is "easy to read." Like when they have a crush on someone and another characters asks them about it and they become red as a pepper saying "n-no! I don't have a crush on him! Of course not!! b-baka!" That's wakariyasui.

気安い

kiyasui
気安い
Relaxed. Familiar. Friendly.
kiyasuku hanashi-kakenaide
気安く話しかけないで
Don't talk [to me] familiarly.
(i.e. don't talk to me like you know me, don't talk to me unless it's something important, etc.)