claus ‧ tro ‧ pho ‧ bi ‧ a /ˌklɔːstrəˈfəʊbiə $ ˌklɒːstrəˈfoʊ-/ BrE AmE noun [uncountable]
[ Date: 1800-1900 ; Language: Modern Latin ; Origin: Latin claustrum 'bar keeping a door closed' ( ⇨ ↑ cloister ) + Modern Latin phobia 'fear' ]
a strong fear of being in a small enclosed space or in a situation that limits what you can do ⇨ agoraphobia
—claustrophobic adjective :
I get claustrophobic in elevators.
a claustrophobic atmosphere