(finance) Paid for by an individual or group. / (by extension, idiomatic) At one's responsibility. / (figuratively) In a way as to harm somebody or something; to the detriment of.

Alternative spelling of at death's door

(UK, Navy) A warrant officer or chief petty officer responsible for discipline aboard a naval ship.

(idiomatic, informal, chiefly in the negative) To do two normally trivial tasks at the same time.

plural of master-at-arms

(baseball) A final resolution to a batter's turn at the plate which does not result in a walk, a hit by pitch, a sacrifice hit or sacrifice fly, or catcher interference

(slang) To perform cunnilingus.

(baseball) In the batter's box.

plural of official at-bat

(baseball, used by play-by-play announcers) A situation in which an ineffective pitcher is pitching with the bases loaded.