充填[juuten] fill (up)
装填[souten] charge
填める[uzumeru] to cover
填める[hameru] to insert
填め込む[hamekomu] to inlay

填る[hamaru] to fit
補填[hoten] compensating
填補[tenpo] supplementation
填り役[hamariyaku] well-suited role
填隙[tengeki] caulking

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

哀詞[aishi] message of condolence
一段動詞[ichidandoushi] ichidan verb (one of the two main conjugation classes of verbs in modern Japanese, usually ending in -eru or -iru)
可能動詞[kanoudoushi] potential verb
歌詞[kashi] song lyrics
賀詞[gashi] congratulations

賀詞交換[gashikoukan] New Year greetings (parties)
冠詞[kanshi] article
感動詞[kandoushi] interjection
間投詞[kantoushi] interjection
疑問詞[gimonshi] interrogative word