washbasin vs lavabo

washbasin and lavabo both are nouns.

Word	Noun	Adjective	Verb	Adverb
washbasin	Yes	No	No	No
lavabo	Yes	No	No	No

As nouns, washbasin and lavabo are synonyms defined as:

Other synonyms of washbasin include handbasin, wash-hand basin, washbowl.

washbasin (noun)	lavabo (noun)
a basin for washing the hands	a basin for washing the hands
a bathroom sink that is permanently installed and connected to a water supply and drainpipe; where you can wash your hands and face