Many classes of compounds with C–O–C linkages are not considered ethers: Esters (R–C(=O)–O–R′), hemiacetals (R–CH(–OH)–O–R′), carboxylic acid anhydrides (RC(=O)–O–C(=O)R′).
There are compounds which, instead of C in the  linkage, contain heavier group 14 chemical elements (e.g., Si, Ge, Sn, Pb). Such compounds are considered ethers as well. Examples of such ethers are silyl enol ethers  (containing the  linkage), disiloxane  (the other name of this compound is disilyl ether, containing the  linkage) and stannoxanes  (containing the  linkage).