wasteweir vs spillway

wasteweir and spillway both are nouns.

Word	Noun	Adjective	Verb	Adverb
wasteweir	Yes	No	No	No
spillway	Yes	No	No	No

As nouns, wasteweir and spillway are synonyms defined as:

wasteweir and spillway: a channel that carries excess water over or around a dam or other obstruction

Other synonyms of wasteweir include spill.

wasteweir (noun)	spillway (noun)
a channel that carries excess water over or around a dam or other obstruction	a channel that carries excess water over or around a dam or other obstruction