About: A Mantra

Mantra is a religious or mystical syllable or poem, typically from the Sanskrit language. Mantras are primarily used as spiritual conduits, words or vibrations that inculcate concentration in the devotee. Mantras are also integrated in religious rituals to remove obstacles, avoid danger, reduce foes, or accumulate wealth. Mantras got their origin from the Vedas of India.

Mantra - The Word
The word "Mantra" has been derived from Sanskrit. Mantra contains two words - "man" which means "to think" (also in manas "mind") and suffix "tra" which means "tool", hence a literal translation would be "instrument of thought". A mantra is a powerful word or phrase that may or may not have meaning in the same way as a sentence.

What is Mantra?

Mantras are single or strung together syllables. It is important to pronounce the mantra properly with an understanding of its meaning. Improper pronunciation of Mantra can inflict losses. So, one should be careful while chanting mantra.

Mantras are energy-based sounds. The Indian metaphysical tradition explains that the body is composed of the combination of five elements and the first of them is sound. Studies in sound symbolism suggest that vocal sounds have meaning whether we are aware of it or not. And certainly there can be multiple layers of symbolism associated with each sound. So even, if we do not understand them, mantras are not meaningless; no vocal utterance is entirely without meaning.

One's subconscious mind can find its solution through meditation and recitation of mantras. A mantra, when repeated constantly during meditation, first loudly and then through silent and mental chanting, changes the consciousness.

Several definitions
Definition # 1: Mantras are energy-based sounds.
Definition #2: Mantras create thought-energy waves.
Definition #3: Mantras are tools of power and tools for power.

Mantras written on a rock in Nepal, pic. found on the net