Do you know ghouls from goblins and ghosts?
Old English swellan "grow or make bigger" (past tense sweall, past participle swollen), from Proto-Germanic *swelnanan (cf. Old Saxon swellan, Old Norse svella, Old Frisian swella, Middle Dutch swellen, Dutch zwellen, Old High German swellan, German schwellen), of unknown origin.
early 13c., "a morbid swelling," from swell (v.). In reference to a rise of the sea, it is attested from c.1600. The meaning "wealthy, elegant person" is first recorded 1786; hence the adjectival meaning "fashionably dressed or equipped" (1810), both from the notion of "puffed-up, pompous" behavior. The sense of "good, excellent" first occurs 1897, and as a stand-alone expression of satisfaction it is recorded from 1930 in American English.
Excellent; wonderful; superb: The hotels are swell/ He was a hell of a swell fellow (1888+)adverb
: The new owners have treated me swell (1920s+)noun
[perhaps fr the late 18th-century phrase cut a swell, ''swagger,'' describing the behavior of a person who swells with arrogance]