Aspro[1] is a contract bridge bidding convention devised by Terence Reese[2] as a British variant on the Astro convention[3] to intervene over a 1NT opening bid.
Like Astro, Aspro is initiated by a 2-level overcall in a minor suit when the overcaller or intervenor[4] holds an unbalanced hand with at least nine cards in two suits (i.e. 5 in one and 4 in the other), at least one of which is a major.
2♣ shows hearts and another suit, and
2♦ shows spades and a minor suit.
^The name is borrowed from a popular British brand of aspirin.
^In the description of competitive bidding, players are referred to as either the Opener (the first to make a bid), the Intervenor (the opponent who makes his side’s first bid), the Responder (partner of the Opener) or the Advancer (partner of the Intervenor).