Select the INCORRECTLY spelt word.

argyu

The incorrectly spelled word is "argyu" (Option 4).

Explanation:

1. Vague: This word is correctly spelled. It means unclear, imprecise, or lacking definite shape, form, or meaning.

2. Tongue: This word is correctly spelled. It refers to the movable muscular organ in the mouth used for tasting, licking, swallowing, and speaking.

3. Vogue: This word is correctly spelled. It refers to something that is currently fashionable or popular.

4. Argyu: This is the misspelled form of the word "argue," which means to present reasons or evidence to support or oppose an idea or proposition. The correct spelling is "argue," with the letter "e" at the end.