Answer:

sexes

AnswerCrossword Clue
SEXESSides in unending battle
SEXESBattle of the ...
SEXESMales and females
SEXESTraditional "battlers"
SEXESGenders
SEXESMale and female
SEXESNoted battlers
SEXESTraditional battlers
SEXESProverbial battlers
SEXESMakes more appealing, with "up"
SEXESPair constantly doing battle?
SEXESSnazzes (up)
SEXESBattle of the ..
SEXESClassic battle participants
SEXESChecks newly-hatched chicks, in a way
SEXESBattle participants?
SEXESChecks chicks
SEXESFrequent battlers?
SEXESSides in a classic battle
SEXESPerennial battlers
SEXESPerennial battlers?
SEXES... up (makes more exciting)
SEXESThe protozoan Tetrahymena has 7
SEXESClassifies, as kittens
SEXESSides in an age-old battle
SEXESLong-time battlers
SEXESWarring factions, sometimes
SEXESSpecies subgroups
SEXESLongtime battlers?
SEXESAge-old battle participants
SEXESIncreases the appeal of, with "up"
SEXESSpecies divisions
SEXESClassic battle sides
SEXESMakes hotter, with "up"
SEXESSides in a longstanding battle
SEXESMakes more attractive, with "up"
SEXESSpices (up)
SEXESGenders.
SEXESThurber's great battle, in cartoons.
SEXESParticipants in Thurber "war."