The term trivial is frequently used
for objects (for examples, groups or topological spaces) that
have a very simple structure or being the simplest possible
case.

Trivial also refers to solutions to an equation
that have a very simple structure, but for the sake of completeness
cannot be omitted. These solutions are called the trivial
solution.

Example:

consider the differential equation y' =
y

where y = f(x) is a function whose derivative
is y'.