1. Not capable of undergoing fission

Antonym: fissionable

• family Termitidae
• family Testudinidae
• family Tethyidae
• family Tetragoniaceae
• family Tetranychidae
• family Tetraodontidae
• family Tetraonidae
• family Tettigoniidae
• family Theaceae
• family Thelephoraceae
• family Thelypteridaceae
• family Theophrastaceae
• family Theraphosidae
• family therapy
• family Theridiidae
• family Thiobacteriaceae
• family Thraupidae
• family Threskiornithidae
• family Thripidae
• family Thymelaeaceae
• family Tiliaceae
• family Tilletiaceae
• family Timaliidae
• family Tinamidae
• family Tineidae