The molecular geometry of NH3 (ammonia) is trigonal pyramidal.
Explanation: In NH3, the central nitrogen atom is bonded to three hydrogen atoms and has one lone pair of electrons. The presence of this lone pair causes the molecule to adopt a trigonal pyramidal shape rather than a trigonal planar shape. The lone pair exerts a greater repulsive force than the bonding pairs, pushing the hydrogen atoms slightly closer together and giving the molecule a pyramidal shape.