Description and Properties

Alcohol = ROH. IUPAC: longest chain containing OH, -e → -ol, lowest locant to OH (e.g. propan-2-ol, 4,5-dimethylhexan-2-ol). Common naming: alkyl group + 'alcohol' (ethyl alcohol, isobutyl alcohol).
When a higher-priority group is present (carboxylic acid, aldehyde, ketone), OH is demoted to the prefix hydroxy- instead of the -ol suffix.
Phenol = OH on a benzene ring. Substituent position named ortho (adjacent, C2), meta (one away, C3), or para (opposite, C4) relative to OH.
Phenols are far more acidic than alcohols: the phenoxide conjugate base is resonance-stabilized into the ring, so phenol donates protons readily.
Hydrogen bonding (from the electronegative O-H) gives alcohols higher boiling/melting points than comparable hydrocarbons; more OH groups per molecule → higher boiling point.

Compound	pKa
Ethanol	≈ 15.9 (weakest)
Methanol	≈ 15.5
Water	≈ 14 (some sources: 15.7)
Phenol	≈ 10 (strongest — resonance-stabilized phenoxide)

Hydroxy- prefix: Used for an OH group when a higher-priority group (carboxylic acid, aldehyde, ketone) is present and takes the parent suffix instead.
Phenoxide ion: Conjugate base of phenol; the negative charge on oxygen delocalizes into the aromatic ring by resonance, stabilizing it and making phenol strongly acidic.
Intermolecular vs. intramolecular forces: Intermolecular (dipole-dipole, H-bonding, London dispersion) act between separate molecules and set physical properties (boiling point, solubility); intramolecular (covalent bonds) hold atoms together within one molecule and set chemical identity.
Hydrogen bonding: A strong dipole-dipole interaction between H (bonded to O, N, or F) and a lone pair on another electronegative atom nearby; drives alcohols' elevated boiling points.

Ortho/meta/para is a general disubstituted-benzene naming convention, not exclusive to phenols — don't assume it only applies when OH is present.
A lower pKa means a stronger acid — phenol (pKa ≈ 10) is the strongest acid in this comparison despite having the smallest number.
Don't confuse the -ol suffix rule with the hydroxy- prefix rule — which one applies depends entirely on whether a higher-priority group (acid/aldehyde/ketone) is also present in the molecule.

Why is phenol so much more acidic than a typical alcohol?

What determines whether OH is named as the -ol suffix or the hydroxy- prefix?

Where is the substituent in a meta-substituted phenol relative to the OH group?

Why do alcohols have higher boiling points than hydrocarbons of similar molecular weight?

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