Noun
subinterval (plural subintervals)
Any of several smaller intervals into which a larger one is divided
Definition Partitions of an interval A partition of an interval is a finite sequence of numbers of the form Each is called a subinterval of the partition. Source: Internet
In other words, it is a partition together with a distinguished point of every subinterval. Source: Internet
The degree n Newton–Cotes quadrature rule approximates the polynomial on each subinterval by a degree n polynomial. Source: Internet
Thus Δϕ, the length of each subinterval, is equal to b − a (the total length of the interval), divided by n, the number of subintervals. Source: Internet