Reducing fractions to their lowest terms involves division. Some books use simplest form to mean the same thing So 5 9 is written in lowest terms since 5 and 9 have no common factors other than 1. A fraction is reduced to lowest terms or simplified when its numerator and denominator have no common factors.
In Algebra a term is either a single number or variable or numbers and variables multiplied together.
The idea of reducing a fraction to its lowest terms means to take a fraction and express it in terms of its simplest possible form by having a fraction that has the same value as the original fraction but it all possible common factors between the numerator and denominator have been simplified. 23 is the simplest form of 46. 23 is in its lowest terms. Minimal in magnitude lowest in rank or importance.