1. Between the ages of 35 and 60
2. Is a lesbian
3. Is heavy set
4. Works in various service industries including postal worker, bank teller, plumber, firefighter, construction worker, and/or Wal-Mart greeter
5. Has a short, manly haircut
As a bonus way to identify a Mare, many Mares often enjoy enjoy eating at Ryan's buffet, or "the trough." They can also be spotted wearing sweatpants, plaid, moo moos, and wrangler jeans.
See also: Filly
Dad: "No son, that was just a Mare. Her hide is tougher than a thousand sheets of steel."