infantry

Short definition from Wiktionary

Noun

1. 1
   Soldiers who fight on foot (on land), as opposed to cavalry and other mounted units, regardless of external transport (e.g. airborne).
2. 2
   The part of an army consisting of infantry soldiers, especially opposed to mounted and technical troops.
3. 3
   A regiment of infantry.
4. 4
   Infants; children.