In chemistry, the term amide (/ˈæmaɪd/ or /ˈæmɪd/ or /ˈeɪmaɪd/)^[1][2][3] is a compound with the functional group R_nE(=O)_xNR₂, where n and x may be 1 or 2, E is some element, and each R represents an organic group or hydrogen.^[4] It is a derivative of an oxoacid R_nE(=O)_xOH with an hydroxy group –OH replaced by an amine group –NR₂.

Some important subclasses are

• carboxamides, or organic amides, where E = carbon, with the general formula RC(=O)NR₂.
• phosphoramides, where E = phosphorus, such as R₂P(=O)NR₂
• sulfonamides, where E = sulfur, namely RS(=O)₂NR₂

The term amide may also refer to

• amide group, a functional group –C(=O)N= consisting of a carbonyl adjacent to a nitrogen atom.
• cyclic amide or lactam, a cyclic compound with the amide group –C(=O)N– in the ring.
• metal amide, an ionic compound ("salt") with the azanide anion H₂N⁻ (the conjugate base of ammonia) or to a derivative thereof R₂N⁻.

There is also a neutral amino radical (•NH₂) and a positively charged NH₂⁺ ion called a nitrenium ion, but both of these are very unstable.