suck·ling [sucklingsucklings] BrE [ˈsʌklɪŋ] NAmE [ˈsʌklɪŋ] noun (old-fashioned) a baby or young animal that is still drinking milk from its mother see out of the mouths of babes (and sucklings) at ↑mouthn.
Word Origin: Middle English: from the verb ↑suck + ↑-ling.