Possible Clues:

• Not fem. or neut
• Gender abbr
• Meanly, in nouns (abbr.)
• Fem. opposite
• Neither fem. nor neut
• Opposite of feminine: Abbr
• Like the Sp. 'el'
• Like some nouns, in Ger.
• Neither fem. nor neut.
• Like Span. o-ending nouns