Merriam-Webster Collegiate Dictionary - mantis

 noun  (plural ~es; also mantes)  Etymology: New Latin, from Greek, literally, diviner, prophet; akin to Greek mainesthai to be mad — more at mania  Date: 1646 any of an order or suborder (Mantodea and especially family Mantidae) of large usually green insects that feed on other insects and clasp their prey in forelimbs held up as if in prayer MANTISSA  noun  Etymology: Latin mantisa, ~ makeweight, from Etruscan  Date: 1846 the part of a logarithm to the right of the decimal point