opportunist vs timeserving

opportunist is a noun but timeserving is not a noun.

Word	Noun	Adjective	Verb	Adverb
opportunist	Yes	Yes	No	No
timeserving	No	Yes	No	No

As adjectives, opportunist and timeserving are synonyms defined as:

opportunist and timeserving: taking immediate advantage, often unethically, of any circumstance of possible benefit

Other synonyms of opportunist include opportunistic.

opportunist (noun)	timeserving (noun)
a person who places expediency above principle

opportunist (adjective)	timeserving (adjective)
taking immediate advantage, often unethically, of any circumstance of possible benefit	taking immediate advantage, often unethically, of any circumstance of possible benefit