ACT - Something done, a deed.
ANT - Any of various insects in the family Formicidae in the order Hymenoptera, typically living in large colonies composed almost entirely of flightless females.
CAT - Any similar animal of the family Felidae, which includes lions, tigers, bobcats, etc.
CON - To study, especially in order to gain knowledge of.
NOT - Negates the meaning of the modified verb.
TAN - A symbol of the trigonometric function tangent.
TIN - A malleable, ductile, metallic element, resistant to corrosion, with atomic number 50 and symbol Sn.
NIT - The egg of a louse.
OAT - Widely cultivated cereal grass, typically Avena sativa.
TIC - A local and habitual convulsive motion of certain muscles.
COAT - An outer garment covering the upper torso and arms.
COIN - A piece of currency, usually metallic and in the shape of a disc, but sometimes polygonal, or with a hole in the middle.
ICON - An image, symbol, picture, or other representation usually as an object of religious devotion.
INTO - Going inside (of).
ANTI - Describing a torsion angle between 90° and 180°.
IOTA - The ninth, and smallest, letter of the Greek alphabet.
TACO - A Mexican snack food; a small tortilla with some rice, beans, cheese, diced vegetables (usually tomatoes and lettuce, as served in the United States) and salsa.
TONIC - Pertaining to tension, especially of muscles.
ANTIC - Grotesque, incongruous.
ACTION - Something done so as to accomplish a purpose.