"sounds fun" or "sounds like fun"

Question

If you say, "it is fun playing golf", I think "fun" is a noun.
When I hear people say, "it sounds fun," is it a noun or an adjective?
I understand the verb "sound" is followed either by a noun or an adjective, and I think they should say, "it sounds like fun" if they use it as a noun. Or can the word "fun" be used as an adjective on its own?
Please clear this up once and for all.

Answer 1

Please clear this up once and for all.

On 15 April 1755, Samuel Johnson "arguably the most distinguished man of letters in English history", published his Dictionary of the English Language in order to "remove rubbish and clear obstructions from the paths of Learning and Genius." It is among the most influential dictionaries in the history of the language. Yet it can do little to prevent people from misusing the word fun.

When enough people misuse a word often enough, it becomes part of the language. It can't really be prevented, no matter how many knuckles are rapped by irritable grammarians.

"That sounds fun!" is creeping into our language, perhaps influenced by a generation of people who want to shorten their communication to far fewer than 140 characters. Nothing can be done about it, for as Robert Burns explained,

The best-laid schemes o' mice an 'men
Gang aft agley
An'lea'e us nought but grief an' pain,
For promis'd joy!

It sounds fun means It sounds like fun. Might as well adjust to it.

Behold Samuel Johnson. Does he look like a fun guy?

Answer 2

The word "fun" is a noun while the word "sound" can be either a verb or a noun. When it is used in a sentence such as " " That sounds fun." It is an error of omission resulting from the contraction of "That sounds like fun" and when we read or hear the phrase "that sounds fun" the contraction naturally "feels" uncomfortable or awkward since it is unbalanced and incomplete, unless one has been introduced to English on "Twitter"