Definition of plain suit in English:

plain suit

noun

  • (in bridge and whist) a suit that is not trumps.

    • ‘For the sake of clarity, it is worth pointing out that where a lead of a plain suit has been trumped by the second player to a trick and the third to play also has no cards in the suit led, then the third player must still overtrump if possible.’
    • ‘The second player to any lead must follow suit if able; must trump if able when void of a plain suit lead; and in any case must win the trick if he can.’
    • ‘The suit of the lowest of these cards, in plain suit order, determines trumps.’
    • ‘The remaining cards comprise 4 plain suits, in each of which the cards rank A, T, K, Q, 9, 8, 7 (lowest).’
    • ‘If a plain suit lead has been trumped, it is illegal to undertrump unless by doing so one creates a K-Q or K-Q-J combination in the trick.’