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

開け閉て[aketate] opening and shutting
開閉[kaihei] opening and shutting
基地閉鎖[kichiheisa] (military) base closing
自閉症[jiheishou] autism
腸閉塞[chouheisoku] intestinal obstruction

閉まる[shimaru] to be shut
店閉まい[misejimai] closing up shop
閉ざす[tozasu] to shut
閉じる[tojiru] to close (e.g. book, eyes, meeting, etc.)
閉込める[tojikomeru] to lock up