In geometry, bisection is the division of something into two equal or congruent parts. Usually it involves a bisecting line, also called a bisector. The most often considered types of bisectors are the segment bisector, a line that passes through the midpoint of a given segment, and the angle bisector, a line that passes through the apex of an angle . In three-dimensional space, bisection is usually done by a bisecting plane, also called the bisector.

भूमिति में, समद्विभाजन किसी वस्तु का दो समान या सर्वांगसम भागों में विभाजन है। सामान्यतः इसमें एक रेखा शामिल होती है, जिसे समद्विभाजक कहा जाता है। समद्विभाजक के प्रायः माने जाने वाले प्रकार हैं खण्ड समद्विभाजक और कोण समद्विभाजक ।