noun
General term for how well something works, especially medicine, treatments, or methods. 効き is common for medicinal contexts.
この薬はよく効きが現れる。
This medicine shows its effectiveness quickly.
新しい治療法の効きを確かめる。
Check the efficacy of the new treatment.
noun, used as a suffix, noun, used as a prefix
dominance (of hand, eye, etc.)
Only when written 利き
Used as a prefix or suffix to indicate which side is dominant, e.g., 利き手 (dominant hand), 右利き (right-handed).
私は右利きなので、右手で字を書く。
I'm right-handed, so I write with my right hand.
利き目を調べる簡単なテストがある。
There's a simple test to check your dominant eye.
noun
Only when written 利き
Refers to the act of tasting to judge quality, often used in contexts like sake tasting (利き酒) or tea tasting (利き茶).
See also: 聞き (きき)
彼は利き酒の達人だ。
He is a master of sake tasting.
利き茶の会に参加した。
I participated in a tea tasting event.
Derived from the verb 利く (きく, 'to be effective'). The kanji 利 suggests advantage or benefit, while 効 emphasizes medicinal efficacy.