In this post I want to highlight a common and important word in the Japanese language, “yoku”. It can be written in hiragana as よく, and depending on the meaning can also be written in kanji as 良く or 欲.
The first meaning I would like to go over is the most common one, which is where “yoku” represents the adverbial form of the adjective “yoi” (よい or 良い), which means “good”. In casual language the form “ii” (いい) is used much more frequently, however you can still use “yoi” in conversations if you prefer.
Being an adverbial form of “good”, here “yoku” means something like “in a good way”, or simply “well”. Let’s look at a simple example:
- 日本語はよく分かりません (nihongo wa yoku wakarimasen)
- I don’t understand Japanese well.
Here “yoku” modifies the verb “wakarimasen” (the negative, polite form of “wakaru”, to understand). In cases like this you can also write it as 良く.
The word “yoku” also has a slightly different meaning which is “frequently” or “often”, and this doesn’t necessarily have to be positive. For example:
- 僕はよく散歩する (boku wa yoku sanpo suru)
- I go on walks often.
While literally this can mean “I go on walks in a good way”, from context we can tell it means simply “often”.
Here’s another example, using text you might find on a drink.
- よく振ってから飲みましょう (yoku futte kara nomimashou)
- Let’s shake it well before drinking.
Here, “often” doesn’t make sense, and we can see that “well” is the proper meaning, with reference to the verb “furu” (to shake).
Another meaning, this one perhaps a bit surprising, is that “yoku” can be used to express surprise (or sometimes disgust) on the part of the speaker. For example:
- よくあんな珍しいものを見つけたね (yoku anna mezurashii mono wo mitsuketa ne)
- I’m surprised you found such a rare thing.
Here the nuance is that the person who found a rare thing did a “good” job, in other words did something that was difficult or unexpected.
By the way, the word “yokumo” よくも is the word “yoku” plus the particle “mo” (the latter acting for emphasis), and especially used in cases where surprise is being expressed.
- よくもここまで来られた (yokumo koko made korareta)
- I’m surprised you came this far.
Note that “I’m surprised” is not a literal translation and just one way to translate this. Depending on the situation other things could be used, like “You did a wonderful job coming this far”, etc.
Another way you often see “yoku” is in the form “yoku nai” (or “yoku arimasen”) which is the negative of “ii” / “yoi”, meaning “bad”.
- 結果はよくないだろうね (kekka wa yoku nai darou ne)
- I bet the result will not be good.
- このモニターの画質はよくないよ (mono monitaa no gashitsu wa yoku nai yo)
- The visual quality of this monitor is not good.
The other main meaning for “yoku” is “desire”, “greed”, or “lust”, and can be written in kanji as 欲. Because this is a noun, it is generally easy to distinguish from the other “yoku” we just talked about (which is an adverb). Here is an example:
- あいつは欲の深い人だ (aitsu wa yoku no fukai hito da)
- He/she is a person with strong desires.
This meaning sounds a bit literary/formal to me, and isn’t used that much in daily life. More common is compound words that contain “yoku”:
- 欲望 (yokubou): desire, lust
- 欲求（yokkyuu): desire
- 欲深い (yokubukai): greedy
- 欲張る (yokubaru): to be greedy (verb)