hole-and-corner vs undercover

hole-and-corner and undercover both are adjectives.

Word	Noun	Adjective	Verb	Adverb
hole-and-corner	No	Yes	No	No
undercover	No	Yes	No	No

As adjectives, hole-and-corner and undercover are synonyms defined as:

hole-and-corner and undercover: conducted with or marked by hidden aims or methods

Other synonyms of hole-and-corner include clandestine, cloak-and-dagger, hugger-mugger, hush-hush, secret, surreptitious, underground.

hole-and-corner (adjective)	undercover (adjective)
conducted with or marked by hidden aims or methods	conducted with or marked by hidden aims or methods
relating to the peripheral and unimportant aspects of life