From Middle Englishsukelen; probably a back-formation of Middle Englishsukeling(“a suckling; infant”), formally equivalent to suck +-le(frequentative suffix). See suckling.
1638, Thomas Herbert, “Travels begun Anno 1626”, in Some yeares travels into divers parts of Asia and Afrique, London: Jacob Blome and Richard Bishop, Book 1, p. 26:
[…] the body of this fish [the Mannatee] is commonly 3 yards long and one broad, slow in swimming, wanting fins, in their place ayded with 2 paps which are not only suckles but stilts to creep a shoare upon such time she grazes […]
An act of suckling
The baby was having a suckle at its mother's breast.
Verb
suckle (third-person singular simple presentsuckles, present participlesuckling, simple past and past participlesuckled)
But out of the woman’s great brown breast the milk gushed forth for the child, milk as white as snow, and when the child suckled at one breast it flowed like a fountain from the other, and she let it flow.
(transitive) To nurse from (a breast, nursing mother, etc.).