Differences Between 切る (kiru) and 尽くす (tsukusu) as Suffix

Meaning of 切る

切る (kiru) generally means “to cut”, as in 野菜やさいを切る means “cut vegetables”. It also means “turn/switch off (an electronic device)”, as in “携帯電話けいたいでんわの電源でんげんを切る” means “switch off a mobile phone”.

Meaning of 尽くす

尽くす (tsukus) means “to devote oneself” as in 彼女に尽くす means “devote oneself to one’s girlfriend”. It also means “to dedicate (everything)”, as in 全力を尽くす means “dedicate all power/energy one has” and ベスト/最善さいぜんを尽くす means “do one’s best”.

Meaning of 切る and 尽くす as Suffix

Both 切る and 尽くす are used as suffix and combined with verbs (e.g. やり切る/やり尽くす) to add the sense of “completely”. However, there are some differences as follows:

• 切る often emphasises the sense of “accomplish”
• 尽くす puts more focus on the fact that things are exhausted/nothing is left.

For instance, if you’re stranded in the middle of a forest and end up eating all food you have, you’d say 食べ尽くしてしまった, whereas if you finish eating 5kg steak in competitive eating, 食べ切った is more natural. Similarly,  やり切った is often used when you have done something with all you have and don’t have any regret (regardless of the outcome), whereas やり尽くした often suggests you’ve tried all means and there is nothing left you can do.

That said, this rule doesn’t always hold true because it’s language. For instance, some verbs are used only with either of them, e.g. 楽しみ尽くす (“to fully enjoy”) and {信しんじ/使つかい/飲のみ}切る (“to completely believe/use/drink”) are much more common than 楽しみ切る and {信じ/使い/飲み}尽くす. Regarding 使う and 飲む, they are actually used with other suffixes: “使い果はたす” and “飲み干ほす”, both of which emphasise the “things are exhausted” sense like 尽くす.