Rare/archaic. Transitive (and occasionally intransitive) verb meaning ‘to make or become soft, smooth and lustrous like silk; to dress or cover with silk’.
lisserEn parlant surtout des cheveux ou d’une matière ; sens de rendre plus doux et plus brillant.
The conditioner promises to silken her hair, leaving it glossy and manageable.
L'après-shampoing promet de lisser ses cheveux, en les rendant brillants et souples.