(ambitransitive) To swell or rise above (something, especially the rim of a container, the sides of something hollow, etc.).
In some years the river overswells its banks, causing widespread flooding.
1768, Ignatius Sancho, letter to Mr. M—, in Letters of the Late Ignatius Sancho, London: J. Nichols, 3rd edition, 1784, p. 13,
[…] the heart gratefully throbbing—overswelled with thankful sensations
(ambitransitive) To cause (something) to be too swollen or large; to become too swollen or large.
1885, Richard Burton, The Book of the Thousand Nights and a Night, The Burton Club, Volume 1, Translator’s Foreward, p. xvi,
My annotations avoid only one subject, parallels of European folk-lore and fabliaux which, however interesting, would overswell the bulk of a book whose speciality is anthropology.
noun
An excessive or sudden increase or flood (of something).
1983, Kenneth A. McClane, “From a Silent Center” in A Tree Beyond Telling, San Francisco: Black Scholar Press, p. 31,
when no Jihad / opens the conceived / to distention, the reedy creek / to overswells / of mudwallow: