i-adjective
vaguely embarrassed; ashamed for no clear reason
Describes a feeling of embarrassment or shame that arises without an obvious cause, often in social situations. The word is relatively rare and literary.
初対面の人と話していると、なぜかそらはずかしい気持ちになる。
When talking with someone I've just met, I feel vaguely embarrassed for some reason.
恥ずかしい is the common word for 'embarrassed' or 'ashamed', usually with a clear reason. 空恥ずかしい adds the nuance of groundless or inexplicable embarrassment.
Compound of 空 (そら, 'empty, groundless') and 恥ずかしい (はずかしい, 'embarrassed'). The exact origin is uncertain, but the word likely arose as a literary expression for an unfounded feeling of shame.