井の中の蛙大海を知らず[inonakanokawazutaikaiwoshirazu] parochial
井桁[igeta] well lining
井戸[ido] water well
井戸屋形[idoyakata] well roof
井戸掘り[idohori] well digging

井戸綱[idozuna] well rope
井戸車[idoguruma] well pulley
井戸水[idomizu] well water
井戸側[idogawa] well curb
井戸替え[idogae] well cleaning

堰堤[entei] dam
可動堰[kadouzeki] canal gates
堰き止める[sekitomeru] to dam up
堰く[seku] to dam (up) (stream)
井堰[iseki] dam

堰き止湖[sekitomeko] dammed lake (formed by natural damming of a river, esp. by landslide, volcanic eruption, etc.)
堰板[sekiita] sheeting
堰を切ったよう[sekiwokittayou] gushing forth
堰を切る[sekiwokiru] to break a dam and gush forth
堰塞[ensoku] damming (e.g. a pond)

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