intercalate vs add

intercalate and add both are verbs.

Word	Noun	Adjective	Verb	Adverb
intercalate	No	No	Yes	No
add	No	No	Yes	No

As verbs, add is a hypernym of intercalate; that is, add is a word with a broader meaning than intercalate:

intercalate: insert (days) in a calendar
add: make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of

intercalate (verb)	add (verb)
insert (days) in a calendar	make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of
	make an addition by combining numbers
	determine the sum of
	state or say further
	bestow a quality on
	constitute an addition