bilateral

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Having or formed of two sides; two-sided.
• adjective Affecting or undertaken by two sides equally; binding on both parties.
• adjective Relating to the right and left sides of the body or of a body structure.
• adjective Having or marked by bilateral symmetry.

from The Century Dictionary.

• Having two sides; of or pertaining to two sides; two-sided.
• In botany, having the sides different.
• In biology, having the sides symmetrical.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Having two sides; arranged upon two sides; affecting two sides or two parties.
• adjective (Biol.) Of or pertaining to the two sides of a central area or organ, or of a central axis.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective having two sides
• adjective involving both sides equally
• adjective binding on both parties to an agreement
• adjective having bilateral symmetry
• adjective anthropology involving descent or ascent regardless of sex and side of the family

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective having two sides or parts
• adjective affecting or undertaken by two parties
• adjective having identical parts on each side of an axis