A conclusion drawn about the likely lie of the cards from the previous play and bidding. Inferences are a very important part of the game. Suppose declarer can see this spade suit:
West bid spades, East did not support and West leads a low diamond against South’s heart contract.
The first inference is that spades are probably 6-2: if they were 5-3, East might have supported.
The second inference is that East has the king of spades; if East did not hold the king, West would hold a sequence of honours in the suit and would very likely have led one. You can also infer that West does not hold an honour sequence in diamonds.
