The last letter from hoteL, which is H in the phonetic alphabet, alphA, bravO, charliE, etc.
Find an word which is singular, add an 's' and it becomes plural, and add another 's' it becomes singular again?
Hint: One of answers involves royalty.
Answer: Prince, princes, princess.
Bra, bras, brass.
A similar change is care, cares, caress, but these are not nouns.