To love someone more than anything that exists or has ever existed. This is more than most and cannot be beaten, under any circumstances, especially by the non-existent words "mostestest" and "mostestestest"
Dominic: I love you.

Stephanie: I love you mostest.

Dominic: Nooooo. I must accept my defeat. You really do love me mostest, Steph.
by TheMostCorrectPersonToEverExis February 28, 2018
A term coined to express an amount so great the word "most" just doesn't do it justice.

First used in relation to love... more specifically the love for a certain Cali girl.
by Davey_aye October 7, 2010
Mostest, when someone calls mostest there is nothing that can beat Mostest so if they say tie they can not tie the person who called it wins. Only one person can call it the first to call it wins NO MATTER what.
Boy: love you
Girl: i love you mostest
Boy: no i do

After sometime....
Boy: lets call it a tie
Girl: there are no ties
Boy: dang it!
by RightOn1234 August 14, 2019
Mostest is a childish way to win an argument. More than most.
Malik- I love you!
Jessica- I love you more!

Malik- I love you most!
Jessica- I love you mostest!

Malik- Damn...she got me.
by ThatBlondeChick9999 August 12, 2013