According to Wikipedia Poker is a sport.
"Sport is an activity that is governed by a set of
rules or
customs and often engaged in
competitively.
Sports commonly refer to activities where the
physical capabilities of the competitor are the sole or primary determiner of the outcome (
winning or losing), but the term is also used to include activities such as
mind sports (a common name for some
card games and
board games with little to no
element of chance) and
motor sports where
mental acuity or equipment quality are major factors. Sport is commonly defined as an
organized, competitive and skillful
physical activity requiring commitment and
fair play."
It says sport refers to card games and board games as well as physical sports. There are often several definitions of a word. I think its a misconception of what the word sport means that has arisen that people think a sport has to be physical. Its bascially just any game involving skill thats played on a widespread level.
Its like the misconception of weighing people in kg. Kg is a unit of mass, and weight should be measured in N.