argus-eyed vs alert

argus-eyed is not a noun while alert is a noun.

Word	Noun	Adjective	Verb	Adverb
argus-eyed	No	Yes	No	No
alert	Yes	Yes	Yes	No

argus-eyed (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

argus-eyed (adjective)	alert (adjective)
carefully observant or attentive; on the lookout for possible danger	engaged in or accustomed to close observation
having very keen vision	mentally perceptive and responsive
	quick and energetic

argus-eyed (verb)	alert (verb)
	warn or arouse to a sense of danger or call to a state of preparedness