Lachesis

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Greek Mythology One of the three Fates, the measurer of the thread of destiny.

Century Dictionary and Cyclopedia

1. n. In classical mythology, that one of the three Fates whose duty it was to assign to each individual his destiny; the disposer of lots. She spun the thread or course of life from the distaff held by Clotho.
2. n. In zoöl.:
3. n. A genus of very venomous American serpents of the pit-viper or rattlesnake family (Crotalidæ), having a rudimentary rattle in the form of spine. L. mutus is the deadly bushmaster of South America.
4. n. Agenus of spiders nowcalled Laches.
5. n. A genus of gastropods of the family Pleurotomidæ, of buccinoid figure with mammillated spire, as L. minima. Risso, 1826
6. n. A genus of pseudoneuropterous insects of the family Psocidæ
7. n. A genus of buprestid beetles, erected by Saunders in 1871 upon the African L. abyla, which had been placed in Œdisternon.

Wiktionary

1. n. Greek mythology One of the three Fates, or Moirae, daughter of Zeus and Themis; the measurer of the each thread of life.

WordNet 3.0

1. n. the Greek goddess of fate who determines the length of the thread of life