leftmost
/ˈlɛftmoʊst/Definitions
1. adjective
being on the left side or at the farthest left position
“She sat in the leftmost seat at the dinner table.”
2. noun
the leftmost point, side, or position
“The leftmost corner of the square was the most interesting part.”
3. adverb
to or at the farthest left position
“The player moved leftmost to block the opponent’s shot.”