Meaning of “mass” - Learner’s Dictionary

mass

noun uk us /mæs/
LUMP [ C ]

a solid lump with no clear shape:

The sauce was now a sticky mass in the bottom of the pan.
a mass of sth

B2 a large amount or number of something:

The garden was a mass of flowers.
She had a mass of blond curls.
AMOUNT [ U ]

in physics, the amount of substance that something contains:

One litre of water has a mass of one kilogram.
masses informal

B2 a large amount or number of something:

I've got masses of work to do.
Take some of our paper - we've got masses.
the masses

the ordinary people who form the largest part of society:

He failed to win the support of the masses.

(Definition of “mass noun” from the Cambridge Learner’s Dictionary © Cambridge University Press)