Definition - What does Mahima mean?
Mahima is one of the eight Hindu siddhis, or divine super powers, that may be attained by practices such as meditation or yoga. Mahima is the ability to expand the body to an infinitely large size, or the ability to become bigger than the universe.
The great sage, Patanjali, outlined five ways to obtain siddhis: birth, using herbs, incantations of mantra, self-discipline and samadhi.
Yogapedia explains Mahima
Mahima siddhi is the ability to acquire enormous size. Several examples of this superpower are found in Hindu mythology. In one legend, Hanuman assumed a large form to burn Lanka and to fight Kumbha Karma. In another, Vishnu expanded to such a huge size that he was able to cover all three worlds in just three steps. Hanuman and Vishnu not only possessed all eight siddhis, but also had the ability to pass these superpowers on to others.
There is also a psychic power connected to mahima siddhi called "clairvoyance," or "far seeing." It is believed that only very advanced yogis may achieve mahima siddhi, or any one of the other eight primary siddhis. Even when he/she does, the yogi rarely reveals this achievement.