to say one is sorry (for doing wrong or not doing something)

express remorse, regret

to show that (a person, statement, act etc) is right, reasonable or proper

legitimize, substantiate

to admit or deny that one is guilty

beg, request

to think and offer reasons for (something that seems unreasonable); to reorganize (an industry etc) in order to reduce or end waste in time, labour, expense etc

make excuse; justify