|Origin:||thy 'by that', from thæt; THAT1|
used before two comparative adjectives or adverbs to show that the degree of one event or situation is related to the degree of another one:
The more he eats the fatter he gets.
'When do you want it?' 'The sooner the better.'
used before an adjective or adverb to emphasize that something is bigger, better etc than all others, or as big, good etc as it is possible for it to be:
He likes you the best.
I had the worst headache last night.