Of immense size, extent, or quantity.
Of exceedingly great scope or nature.
A gargantuan effort.
Of a tremendous size, volume, degree, etc.
The definition of gargantuan is enormous or gigantic.
A 10-foot high mountain of chocolate bars would be an example of a gargantuan amount of chocolate.
Origin of gargantuan
From Gargantua, a giant with a very large appetite in Rabelais's The Inestimable Life of Gargantua.