Bisection comes from bisect (Latin bi- 'two' + secāre 'to cut') + the noun-forming suffix -ion. The historical trail runs through bi- in Latin and secāre in Latin. Morphologically, bisection is transparent: it draws on bisect (Latin bi- 'two' + secāre 'to cut') + the noun-forming suffix -ion. Used as a noun, bisection now means "the division of something into two equal parts", so the present definition can be read against the older forms and meanings. The same lexical family is also visible in related forms such as bisect, bisector, and section. The result is a borrowed or transmitted form whose modern spelling carries a compact record of its route into English.