Russian masculine gender
All Russian nouns with a consonant ending are masculine:
There is also a large group of masculine nouns ending in -а,-я which includes nouns denoting male persons and nouns derived from other masculine nouns.
Masculine nouns with other endings are, as a rule, indeclinable nouns borrowed from other languages. Some Russian nouns of foreign origin with ending -е are masculine:
Some Russian nouns with the ending -o are masculine: