a whetstone: と (to), more commonly spelled using 砥 / to polish: みがく (migaku), more commonly spelled using 磨 / to flatten: たいらにする (taira ni suru), more commonly spelled using 平

a hobby (activity done for enjoyment in spare time) / one's taste (set of preferences)

(rare) Synonym of 芥子 (keshi): the opium poppy, Papaver somniferum

指切り: pinky swear, the act of entwining little fingers to seal a promise.