polish, sharpen

(rock) + (open)
★★☆☆☆
9 strokes

Onyomi

KEN

Mnemonic

KENNY polished his rock with an open hand (holding a chemise cloth)

Kunyomi

と*ぐ to grind or hone - usually a knife. But sometimes you can hone a skill, just like in English.
★☆☆☆☆

Jukugo

研究(けんきゅう)

research ★★★☆☆
(polish, sharpen) + (research) = 研究 (research)

研修(けんしゅう)

study, training ☆☆☆☆☆
(polish, sharpen) + (master a skill) = 研修 (study, training )

Synonyms

training
練習    訓練    研修