Late C14: Fyve þousand folk it was as greet mervaille / Wiþ
loves fyve and fisshes two to feede. / God sente his foyson at hir
grete neede. — Geoffrey Chaucer, The Man of Law's Tale
In the context of "mostly|Scottish English": strength, power
French
Etymology
Old French, from Vulgar Latin fusio, from Latin fūsio.