In case of simple ethers, the prefix di is attached before the name of the alkyl group.Examples:
C2H5 - O - C2H5 is Diethyl etherC6H5 - O - C6H5 is Diphenyl ether
C2H5 - O - C6H5 is Dthyl phenyl ether.According to the IUPAC nomenclature ethers are regarded as hydrocarbon derivatives in which a hydrogen atom is replaced by an alkoxy group - OR, the larger group (R) being chosen as the parent hydrocarbon. Ethers are named as alkoxyalkenes. The larger alkyl group forms the part of parent chain while lower alkyl group constitutes the alkoxy radical.
The numbering of the parent chain is done so that the carbon atom linked to the -O-atom gets the lowest number.