(idiomatic) To be dead or finished.

(baseball) An instance where the batter is allowed to go directly to first base without the possibility of being put out, due to the opposing pitcher delivering four balls.

(politics) Alternative form of Leader of the Opposition

Alternative spelling of base on balls

By the route of. / For the purpose of; as a means of; as an instance of; as a type or form of.

Alternative spelling of put out

Alternative spelling of put out

(astronomy) a type of active galaxy with an active galactic nucleus (AGN), named after its prototype, BL Lacertae

In an old-fashioned manner.

(also figuratively) An accessory that can be bolted on or otherwise attached.