agglutinate vs cleave

agglutinate is an adjective but cleave is not an adjective.

Word	Noun	Adjective	Verb	Adverb
agglutinate	No	Yes	Yes	No
cleave	No	No	Yes	No

As verbs, cleave is a hypernym of agglutinate; that is, cleave is a word with a broader meaning than agglutinate:

agglutinate: clump together; as of bacteria, red blood cells, etc.
cleave: come or be in close contact with; stick or hold together and resist separation

Other hypernyms of agglutinate include adhere, cling, cohere, stick.

agglutinate (adjective)	cleave (adjective)
united as if by glue

agglutinate (verb)	cleave (verb)
clump together; as of bacteria, red blood cells, etc.	separate or cut with a tool, such as a sharp instrument
string together (morphemes in an agglutinating language)	make by cutting into
	come or be in close contact with; stick or hold together and resist separation