SASE (self addressed stamped envelope)
R.S.V.P.
The answer is an envelope. It contains a letter.
Finish is another word for completion starting with the letter F.
Well... Alphabet Acronyms Attended Ambience Actually Answered
Liberalness is another word for generosity starting with the letter L.
The word is "envelope" (which usually holds only one letter).
The word its is a possessive form of the pronoun 'it', used as an attributive adjective.It is less awkward than saying 'Put the letter in the letter's envelope' or '... the envelope of the letter'.
A formal or causal letter is usually mailed in an envelope.
Envelope
An 8 letter word, with just one letter in it, is ENVELOPE. 8 letters in the word, 1 letter inside the envelope.
place something in an envelope together with a letter
A business letter sized envelope, the most popular being envelope style #10 measures 4.125 inches x 9.5 inches.