Definition of "waif"

(Britain, law, archaic) Often in the form waif and stray, waifs and strays: an article of movable property found of which the owner is not known, such as goods washed up on a beach or thrown away by an absconding thief; such items belong to the Crown, which may grant the right of ownership to them to a lord of a manor.

(figuratively)

1. Something found, especially if without an owner; something which comes along, as it were, by chance.  examples

2. A person (especially a child) who is homeless and without means of support; also, a person excluded from society; an outcast.  quotations  examples

   Quotations

   • Tenderly Kala nursed her little waif, wondering silently why it did not gain strength and agility as did the little apes of other mothers. It was nearly a year from the time the little fellow came into her possession before he would walk alone, and as for climbing—my, but how stupid he was!

     1912 October, Edgar Rice Burroughs, “Tarzan of the Apes”, in The All-Story, New York, N.Y.: Frank A. Munsey Co.; republished as “The White Ape”, in Tarzan of the Apes, New York, N.Y.: A. L. Burt Company, 1914 June, page 55

   • Only an old woman, bloated, disheveled and bleared. / Far-wandered waif of other days, / Huddles for sleep in a doorway, / Homeless.

     1916 April, Carl Sandburg, “Old Woman”, in Chicago Poems, New York, N.Y.: Henry Holt and Company, page 168

3. (by extension) A very thin person.  quotations  examples

   Quotations

   • When we had done all the things there were to do, he passed out and I clung to his reassuringly solid, soft stomach—paternal, so different to the indie waifs—and cried.

     2021, Megan Nolan, Acts of Desperation‎, Random House

4. (by extension, botany) A plant introduced in a place outside its native range but not persistently naturalized.  examples

(transitive) To cast aside or reject, and thus make a waif.  quotations  examples

(nautical, chiefly whaling, historical) A small flag used as a signal.  quotations

Something (such as clouds or smoke) carried aloft by the wind.  examples