How to Say "waif" in Spanish
The Spanish word for “waif” is “abandonado” — C1 level.
English → SpanishC1
NounC1formal
a neglected or homeless person

Examples
La sociedad trata a los sin techo como abandonados.
Society treats the homeless as outcasts.
Adjective as Noun
Like many Spanish adjectives, 'abandonado' can be used as a noun by placing an article (like 'el' or 'un') in front of it, meaning 'the abandoned one' or 'an abandoned person'.
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