An Etymological Dictionary of Astronomy and Astrophysics

1. Of a line, that portion bounded by two points.
   
2. Of a circle, that portion of a plane bounded by an arc of the circle and its chord.
   
3. Of a sphere, the solid formed between two parallel planes that cut through a sphere.
   
4. In computer science, a portion of a program, often one that can be loaded and executed independently of other portions.

Etymology (EN): From L. segmentum “a strip or piece cut off,” originally a geometric term, from secare “to cut” + -mentum “-ment.”

Etymology (PE): Borank, from Kermâni borang “a slice (of fruit);” Borujerdi boleng “piece, section,” ultimately from *brin-ka- (probable contracted forms Lari peng and pengi “portion or part of anything”), related to boridan “to cut off;” Mid.Pers. brīn-, blyn-, britan, brinitan “to cut off,” Av. brī- “to shave, shear,” brin- (with prefix pairi-);
cf. Skt. bhrī- “to hurt, injure,” bhrinanti “they hurt;” PIE base bhrei- “to cut, pierce.”