Li·bra (l??br?)n.1. A constellation in the Southern Hemisphere near Scorpius and Virgo. Also called Balance, Scales.2. a. The seventh sign of the zodiac in astrology. Also called Balance, Scales.b. pl. Li·bras One who is born under this sign.[Middle English, from Latin L?bra, from l?bra, balance, the constellation Libra.]li·bra (l??br?)n. pl. li·brae (-br??) Abbr. lb. A unit of weight in ancient Rome equivalent to about 12 ounces.[Middle English, from Latin l?bra.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.libra (?la?br?) n, pl -brae (-bri?) (Units) an ancient Roman unit of weight corresponding to 1 pound, but equal to about 12 ounces[C14: from Latin, literally: scales]Libra (?li?br?) n, Latin genitive Librae (?li?bri?) 1. (Astronomy) astronomy a small faint zodiacal constellation in the S hemisphere, lying between Virgo and Scorpius on the ecliptic2. (Astrology) astrology a. Also called: the Scales or the Balance the seventh sign of the zodiac, symbol ?, having a cardinal air classification and ruled by the planet Venus. The sun is in this sign between about Sept 23 and Oct 22b. a person born under this signadj (Astrology) astrology born under or characteristic of Libra Also (for senses 2b, 3): LibranCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014li?bra (?la? br?, ?li-) n., pl. -brae (-br?, -br?). the ancient Roman pound (containing 5053 grains or 327.4 grams). [1350?1400; Middle English