In organic nomenclature, which suffix identifies a compound as a carboxylic acid?

The suffix that identifies a compound as a carboxylic acid is "-oic acid." This designation is crucial in organic nomenclature because it specifies the presence of the carboxyl functional group (-COOH), which defines carboxylic acids. When naming these compounds, the "-oic acid" suffix indicates that the parent hydrocarbon chain has been modified to include this functional group, and it helps signify the chemical properties that accompany it, such as increased acidity compared to hydrocarbons without this functional group.

For example, if we have a carboxylic acid derived from a three-carbon alkane, instead of calling it propanol (which would imply an alcohol), the correct name is propanoic acid, reflecting the presence of the carboxyl group. This naming convention is standard and clearly communicates the compound's identity and functional characteristics to chemists.