Phenols certainly behave like benzene and are therefore aromatic, please note that aromaticity is an experimentally observed feature. You can see the aromaticity from the π type orbitals, that are in both cases quite similar and extensively delocalised.

Why is phenoxide ion aromatic?

Infact, it is due to these resonance characteristics the phenol is highly acidic as there is a partial positive charge on the oxygen atom in the resonance stabilised phenol and the phenoxide ion thus formed itself is resonance stabilised. ...

Which ion is aromatic?

Ions that satisfy Huckel's rule of 4n + 2 π-electrons in a planar, cyclic, conjugated molecule are considered to be aromatic ions. For example, the cyclopentadienyl anion and the cycloheptatrienylium cation are both considered to be aromatic ions, and the azulene molecule can be approximated as a combination of both.