NOUN (2)

1. a commonly repeated word or phrase;
- Example: "she repeated `So pleased with how its going' at intervals like a mantra"

2. (Sanskrit) literally a `sacred utterance' in Vedism; one of a collection of orally transmitted poetic hymns;

The Collaborative International Dictionary of English v.0.48:

Mantra \Man"tra\, n. [Skr.]
   A prayer; an invocation; a religious formula; a charm.
   [India]
   [1913 Webster]

   Note: Among the Hindoos each caste and tribe has a mantra
         peculiar to itself; as, the mantra of the Brahmans.
         --Balfour (Cyc. of India).
         [1913 Webster]

WordNet (r) 3.0 (2006):

mantra
    n 1: a commonly repeated word or phrase; "she repeated `So
         pleased with how its going' at intervals like a mantra"
    2: (Sanskrit) literally a `sacred utterance' in Vedism; one of a
       collection of orally transmitted poetic hymns

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "mantra":
   Agnus Dei, Benedicite, Gloria, Gloria Patri, Gloria in Excelsis,
   Introit, Magnificat, Miserere, Nunc Dimittis, Te Deum, Trisagion,
   Vedic hymn, alleluia, answer, anthem, antiphon, antiphony,
   canticle, chant, chorale, doxology, hallelujah, hosanna, hymn,
   hymn of praise, hymnody, hymnography, hymnology, laud, motet,
   offertory, offertory sentence, paean, psalm, psalmody, report,
   response, responsory, versicle