(idiomatic) something that is difficult or impossible to locate; something impossibly complex or intractable

Try or attempt (something); to give something a try.

The lower limit of dating, as of the earliest plausible date at which a fact could have occurred or a document could have been written.

(Britain, euphemistic, idiomatic) To use the toilet.

plural of A-side

The side of a cassette tape or record that holds the primary track. / (by extension) The track on the A-side of a tape or record. / The first track on a compact disc single.

first rate or excellent / (of a ship) in first class condition

(British) A main or principal road; a trunk road.

plural of A-road

(law) From the time when a law, legal right or decree, contract, ownership interest, partnership (etc.) comes into force.