イン, オン, かく.す, かく.し, かく.れる, かか.す, よ.る, お, がくし
conceal, hide, cover
JLPT1 G7 S14 F1089
The element above 心 in 㥯 was originally 爪 claw/hand + an element combining a symbol in the shape of 工 + another hand → use one hand on top and the other on the bottom to cover and conceal a 工-shaped object. The addition of 心 heart/emotions suggests secrets concealed firmly in the heart. To 㥯# (conceal), 隱 adds 阜 piled earth → earthen wall behind which objects are concealed → *hide/conceal*.
[Full Kanji Etymology List]