sol·dier 
(sōljər)
(sōljər)n.
1. One who serves in an army.
2. An enlisted person or a noncommissioned officer.
3. An active, loyal, or militant follower of an organization.
4.
a. A nonreproductive ant or termite that has a large head and powerful jaws.
b. One of a group of honeybees that swarm in defense of a hive.
intr.v. sol·diered, sol·dier·ing, sol·diers
Phrasal Verb: 1. To be or serve as a soldier.
2. To make a show of working in order to escape punishment.
soldier on
To continue to do something, especially when it is difficult or tedious; persevere: "As Russia decayed, these Siberians soldiered on, finding ways to live and enjoy life" (Jeffrey Tayler).
[Middle English soudier, mercenary, from Anglo-Norman soudeour, soldeier and Old French soudoior, soudier, both from Old French sol, soud, sou, from Late Latin solidum, soldum, pay, from solidus, solidus; see SOLIDUS.]
soldier·ship′ n.