BT Qid 73b(12) :חריפא דנהרא אין בו משום אסופי פשרא יש בו משום אסופי‏ : (an infant) in a fast-flowing river: there is no suspicion of it being a foundling; in melting water there is a suspicion of it being a foundling †
See the entire entry for pšar, pišrā n.m. interpretation; dissolving; cud