Complex sentence: In the strict sense the term "amine oxide" applies only to oxides of tertiary amines including nitrogen-containing aromatic compounds like pyridine, but is sometimes also used for the analogous derivatives of primary and secondary amines.
Split into simpler sentences: In the strict sense the term "amine oxide" applies only to oxides of tertiary amines. Sometimes it is also used for the analogous derivatives of primary and secondary amines.