gap vs lacuna

gap and lacuna both are nouns.

Word	Noun	Adjective	Verb	Adverb
gap	Yes	No	Yes	No
lacuna	Yes	No	No	No

As nouns, lacuna is a hyponym of gap; that is, lacuna is a word with a more specific, narrower meaning than gap:

Other hyponyms of gap include blank, spark gap.

gap (noun)	lacuna (noun)
an act of delaying or interrupting the continuity	a blank gap or missing part
a narrow opening
a conspicuous disparity or difference as between two figures
a difference (especially an unfortunate difference) between two opinions or two views or two situations
an open or empty space in or between things
a pass between mountain peaks; geomorphological term for the lowest point on a mountain ridge between two peaks

gap (verb)	lacuna (verb)
make an opening or gap in