merry vs alert

merry is not a noun while alert is a noun.

Word	Noun	Adjective	Verb	Adverb
merry	No	Yes	No	No
alert	Yes	Yes	Yes	No

As adjectives, merry and alert are synonyms defined as:

Other synonyms of merry include brisk, lively, rattling, snappy, spanking, zippy.

merry (noun)	alert (noun)
	a warning serves to make you more alert to danger
	an automatic signal (usually a sound) warning of danger
	condition of heightened watchfulness or preparation for action

merry (adjective)	alert (adjective)
quick and energetic	engaged in or accustomed to close observation
offering fun and gaiety	mentally perceptive and responsive
full of or showing high-spirited merriment	quick and energetic

merry (verb)	alert (verb)
	warn or arouse to a sense of danger or call to a state of preparedness