The word which is nearest in meaning to the word economical

Opposite of the word 'rigid'

The word which is nearest in meaning to the word 'profound'? 

The bundle is so heavy that I cannot lift it

(Use 'too' instead of `so   that') 

Rahul is very rich. He can buy a car (Combine using 'enough')

The appropriate meaning of 'run-of-the-mill'