sea ladder vs ladder

sea ladder and ladder both are nouns.

Word	Noun	Adjective	Verb	Adverb
sea ladder	Yes	No	No	No
ladder	Yes	No	Yes	No

As nouns, ladder is a hypernym of sea ladder; that is, ladder is a word with a broader meaning than sea ladder:

sea ladder: (nautical) ladder to be lowered over a ship's side for coming aboard
ladder: steps consisting of two parallel members connected by rungs; for climbing up or down

sea ladder (noun)	ladder (noun)
(nautical) ladder to be lowered over a ship's side for coming aboard	steps consisting of two parallel members connected by rungs; for climbing up or down
	a row of unravelled stitches
	ascending stages by which somebody or something can progress

sea ladder (verb)	ladder (verb)
	come unraveled or undone as if by snagging