“A nominal form of verbs in Latin: e.g. pugnando (“fight-gerund-abl.sg”) “by fighting.” Hence a term available for verb forms with a noun-like role in other languages: e.g. English fighting is traditionally a gerund in Fighting used to be fun, as opposed to the participle, also in –ing but with a different syntactic role, in people fighting.”
Excerpted from: Matthews, P.H. The Oxford Concise Dictionary of Linguistics. New York: Oxford University Press, 2014.