Definitions
1.adjectiveHaving much distance from one terminating point on an object or an area to another terminating point (usually applies to horizontal dimensions; see Usage Notes below)."It's a long way from the Earth to the Moon."
2.adjectiveHaving great duration."The pyramids of Egypt have been around for a long time."
3.adjectiveSeemingly lasting a lot of time, because it is boring or tedious or tiring.
4.adjectiveNot short; tall.
5.adjectivePossessing or owning stocks, bonds, commodities or other financial instruments with the aim of benefiting of the expected rise in their value."I'm long in DuPont; I have a long position in DuPont."
6.adjectiveOf a fielding position, close to the boundary (or closer to the boundary than the equivalent short position).
7.adjective(of a ball or a shot) Landing beyond the baseline, and therefore deemed to be out."That forehand is long."
8.adjectiveOccurring or coming after an extended interval; distant in time; far away.
9.adverbOver a great distance in space."He threw the ball long."
10.adverbFor a particular duration."How long is it until the next bus arrives?"
11.adverbFor a long duration."Paris has long been considered one of the most cultured cities in the world."