TOPMOST
topmost, uppermost, upmost
(adjective) at or nearest to the top; “the uppermost book in the pile”; “on the topmost step”
Source: WordNet® 3.1
Etymology
Adjective
topmost (comparative more topmost, superlative most topmost)
At or nearest to the top; uppermost; being the very highest.
Antonyms
• bottom-most
Source: Wiktionary
Top"most`, a.
Definition: Highest; uppermost; as, the topmost cliff; the topmost branch
of a tree.
The nightngale may claim the topmost bough. Cowper.
Source: Webster’s Unabridged Dictionary 1913 Edition