一廓[ikkaku] one block
外廓[gaikaku] outer wall (e.g. castle)
城廓[joukaku] fortress
遊廓[yuukaku] red light district

輪廓[rinkaku] contour
廓清[kakusei] purification
廓詞[kuruwakotoba] sociolect or secret language used by prostitutes in red-light districts (Edo period)

ダイヤの指輪[daiyanoyubiwa] diamond ring
一次線輪[ichijisenrin] primary coil
一輪[ichirin] one flower
一輪車[ichirinsha] unicycle
花輪[hanawa] wreath

競輪[keirin] keirin
金輪際[konrinzai] the deepest bottom of the earth
九輪[kurin] kurin (nine vertically stacked rings of a pagoda finial)
結婚指輪[kekkonyubiwa] wedding ring
月の輪[tsukinowa] moon (esp. full moon)