偏芯[henshin] eccentricity (in mechanics, electronics, etc.)
燈芯[toushin] (lamp) wick
帯芯[obishin] thick obi sash
摘芯[tekishin] thinning (buds and branches)
芯地[shinji] padding

替え芯[kaeshin] spare lead
鉛筆の芯[enpitsunoshin] lead of a pencil
硬の芯[kounoshin] hard pencil lead
林檎の芯[ringonoshin] core of an apple

雲鬢花顔[unbinkagan] beautiful woman (metaphorical)
横顔[yokogao] face in profile
温顔[ongan] kindly face
なに食わぬ顔[nanikuwanukao] innocent look
我物顔[wagamonogao] looking or acting as if one owned the place

汗顔[kangan] ashamed
顔から火が出る[kaokarahigaderu] to be extremely embarrassed
顔を顰める[kaowoshikameru] to grimace
顔を潰す[kaowotsubusu] to make somebody lose face