a heavy vehicle, (especially) a truck with a payload of 6.5 tons or more, or a passenger vehicle seating 30 people or more

Kyūjitai form of 歯車 (“gear”)

hearse (Oxcart used as a hearse for nobles or the emperor in ancient Japan. The wheels had metal spokes that scraped them, producing a screeching resembling sad wailing.)

Synonym of 火車 (“fiery chariot that brings sinners to hell”)

(military) antitank

water truck, a vehicle designed to carry and spray water

(aeronautics) trailing edge

after school

(anatomy) an occiput

a back gate / (figuratively) the anus, as a homophone for 肛門 and in contrast to 前門 (zenmon, “front gate”, figurative for vagina)