Webster's Revised Unabridged Dictionary · 1913

Fay

Fay (fā) , noun

[French fée. See Fate, and compare Fairy.]

A fairy; an elf.
Yellow-skirted fays. — Milton

Fay , noun

[Old French fei, French foi. See Faith.]

Faith; as, by my fay. [Obsolete] — Chaucer

Fay (fā) , transitive verb

[Old English feien, transitive verb & i., Anglo-Saxon fēgan to join, unite; akin to Old Saxon fōgian, Dutch voegen, Old High German fuogen, German fugen, Swedish foga. See Fair, and compare Fadge.]

(Shipbuilding) To fit; to join; to unite closely, as two pieces of wood, so as to make the surface fit together.

Fay , intransitive verb

(Shipbuilding) To lie close together; to fit; to fadge; -- often with in, into, with, or together.
Collocations (1)
Faying surface , that surface of an object which comes with another object to which it is fastened; -- said of plates, angle irons, etc., that are riveted together in shipwork.