/ Dictionary / Index P Pecos: Meaning and Definition of Find definitions for: Pe•cos Pronunciation: (pā'kus, -kōs), [key] — n. a river flowing SE from N New Mexico through W Texas to the Rio Grande. 735 mi. (1183 km) long. a town in W Texas, near the Pecos River. 12,855. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: pecos (Thesaurus) pecky Pecos Bill Related Content Daily Word Quiz: mamba Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language