main

1 main /ˈmeɪn/ adjective
1 main
/ˈmeɪn/
adjective
Britannica Dictionary definition of MAIN
always used before a noun
: most important : chief, principal

— mainly

adverb
2 main /ˈmeɪn/ noun
plural mains
2 main
/ˈmeɪn/
noun
plural mains
Britannica Dictionary definition of MAIN
1 
[count] : the largest pipe in a system of connected pipes
2 
the mains British
a  : the system of pipes or wires for electricity, gas, or water
— often used as mains before another noun
b  : the place where electricity, gas, or water enters a building or room

in the main

: in general — used to say that a statement is true in most cases or at most times