daddy longlegs

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various arachnids of the order Phalangida, with a small rounded body and long slender legs. Also called harvestman.
2. n. See crane fly.

Century Dictionary and Cyclopedia

1. n. In Great Britain, a name of tipularian dipterous insects, or crane-flies, of the family Tipulidæ. Also called father-long-legs and Harry-long-legs.
2. n. In America, a popular name of the opilionine or phalangidean arachnids or harvestmen, spider-like creatures with small rounded bodies and extremely long, slender legs. Also called grandfather-long-legs and granddaddy-long-legs. See Phalangium.

Wiktionary

1. n. UK, Ireland The cranefly; any insect of the family Tipulidae.
2. n. Australia, Canada, New Zealand, US Any (non-spider) arachnid of the order Opiliones, mostly with long thin legs; the harvestman.
3. n. loosely The daddy long-legs spider, any spider of the family Pholcidae.

GNU Webster's 1913

1. (Zoöl.) An arachnidan of the genus Phalangium, and allied genera, having a small body and four pairs of long legs; -- called also harvestman, carter, and grandfather longlegs.
2. (Zoöl.) A name applied to many species of dipterous insects of the genus Tipula, and allied genera, with slender bodies, and very long, slender legs; the crane fly; -- called also father longlegs.

WordNet 3.0

1. n. long-legged slender flies that resemble large mosquitoes but do not bite
2. n. spiderlike arachnid with a small rounded body and very long thin legs