カク, コウ, たし.か, たし.かめる
assurance, firm, tight, hard, solid, confirm, clear, evident
JLPT3 G5 S15 F252
隺 combines 隹 short, squat bird + 冖 cover that obscures → bird obscured by a covering/overhanging object. 確 is as per 隺# (framing object that obscures/is obscured) + 石 stone → obscuring stone wall. *Verify*; *ascertain*, *certain*, *positive*, *reliable* and *sound* (of mind/health) are borrowed meanings.
[Full Kanji Etymology List]