longest
adj.adj. the most length or time compared to everything else in a group. You use this to describe the one thing that goes further or lasts more than any other.
adj. the superlative form of 'long', indicating the greatest extent in space or duration within a specific set. Typically follows 'the' and precedes a noun or stands alone after a linking verb.
The Nile is the longest river in the world.
The longest day of the year occurs in June for people living in the northern hemisphere.
While the shortest route appeared more efficient on the map, the longest path actually saved time by avoiding the heavy congestion of the city center.
long + -est
Superlative form; almost always preceded by the definite article 'the'.
the most longestthe longestSuperlatives of one-syllable adjectives use the '-est' suffix; they do not take 'most'.