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

謂われ[iware] reason
謂わば[iwaba] so to speak
所謂[iwayuru] what is called
謂う[iu] to say
謂う所の[iutokorono] what is called

過ちて改めざる是を過ちと謂う[ayamachitearatamezarukorewoayamachitoiu] to err and not change one's ways, this is what it is to err (from Analects of Confucius)
謂れない[iwarenai] unjustified
謂れ因縁[iwareinnen] origin
謂れのない[iwarenonai] unjustified