一門[ichimon] family
陰門[inmon] (female) genitalia
開門[kaimon] opening gate
凱旋門[gaisenmon] arch of triumph
冠木門[kabukimon] gate with a crossbar

関門[kanmon] barrier
玉門[gyokumon] beautifully decorated gate (euph. for female genitalia)
桑門[soumon] monk
軍門[gunmon] camp gate

下顎[kagaku] lower jaw
二重顎[nijuuago] double chin
顎骨[agobone] jawbone
上顎[uwaago] upper jaw
顎紐[agohimo] chin strap

顎ひげ[agohige] beard (esp. on the chin)
下顎骨[kagakukotsu] mandible
顎関節[gakukansetsu] jaw joint
顎で使う[agodetsukau] to set somebody to work in an arrogant fashion

弁鰓類[bensairui] lamellibranches (i.e. bivalves)
鰓呼吸[erakokyuu] branchial respiration (breathing using gills)
鰓蓋[erabuta] gill cover
鰓孔[eraana] gill slit
鰓裂[sairetsu] gill slit

腸鰓類[chousairui] enteropneusts (hemichordates of class Enteropneusta)
翼鰓類[yokusairui] pterobranchs (hemichordates of class Pterobranchia)
海鰓[umiera] sea pen (any coelenterate of the family Pennatulidae or related families)
板鰓類[bansairui] elasmobranchs