The proper noun (holiday) Thanksgiving has a normal S plural, Thanksgivings.
The spelling is the same in any case, THANKSGIVING.
The plural way to spell studio is studios.
The plural is hooves.
The plural is cherries.
The plural is cantaloupes.
The plural is resources.
The plural is "emeralds."
The plural is roses.
The plural is bridges.
thanksgiving
Trout is plural
The plural of beach is beaches.