One option is the word offer.
No, the word "proposal" is not an adverb.The word "proposal" is a noun.
Suggestion is another word for proposal answer: engagement?
The word is spelled proposal, just as you spelled it. Propose is the root word.
Proposal letters are of many types, for example, business proposal letter, sponsorship or marriage proposal letter. For a better insight you can surf the web. I found a website for you, see if it is useful.
The link below has an example of business proposal letter, hope it will be helpful.
Daily is a good word for a 5 letter word for everyday.
loose is a 5 letter word for not taut.
Inter is a 5-letter word for bury.
small 5 letter word
The 5 letter word for equal is 'alike'.
what 5 letter word begins with s- a living thing-second 5 letter word ending in d
The following source is an example of proposal letter for sponsorship. Hope it works !