weir vs dike

weir and dike both are nouns.

Word	Noun	Adjective	Verb	Adverb
weir	Yes	No	No	No
dike	Yes	No	Yes	No

As nouns, dike is a hypernym of weir; that is, dike is a word with a broader meaning than weir:

weir: a low dam built across a stream to raise its level or divert its flow
dike: a barrier constructed to contain the flow of water or to keep out the sea

Other hypernyms of weir include dam, dyke.

weir (noun)	dike (noun)
a low dam built across a stream to raise its level or divert its flow	a barrier constructed to contain the flow of water or to keep out the sea
a fence or wattle built across a stream to catch or retain fish	(slang) offensive term for a lesbian who is noticeably masculine

weir (verb)	dike (verb)
	enclose with a dike