贋印[nisein] forged seal
贋金[nisegane] counterfeit money
贋作[gansaku] fake
贋手紙[nisetegami] forged letter
贋首[nisekubi] falsified severed head

贋造[ganzou] counterfeiting
贋造紙幣[ganzoushihei] counterfeit paper money
贋者[nisemono] imposter
贋い[magai] imitation

一首[isshu] tanka
鎌首[kamakubi] sickle-shaped neck (e.g. snake, praying mantis)
丸首[marukubi] round-necked (T-shirt)
偽首[nisekubi] falsified severed head
カリ首[karikubi] (something resembling a) goose's neck

がん首[gankubi] head of a pipe, incl. the bowl and stem attachment
機首[kishu] nose (of plane)
襟首[erikubi] nape of neck
元首[genshu] ruler
絞首刑[koushukei] death by hanging