The French terminations -ois / ais serve as both the singular and plural masculine; adding 'e' (-oise / aise) makes them singular feminine; 'es' (-oises / aises) makes them plural feminine.
The Spanish termination "-o" usually denotes the masculine and is normally changed to feminine by dropping the "-o" and adding "-a".
Adjectives ending -ish can be used as collective demonyms (e.g. the English, the Cornish).
So can those ending in -ch / -tch (e.g. the French, the Dutch) provided they are pronounced with a 'ch' sound (e.g. the adjective Czech does not qualify).
(Reference: Ethnologue, Languages of the World) a Burma is also known as Myanmar.