while 
(wīl, hwīl)
(wīl, hwīl)n.
1. A period of time: stay for a while; sang all the while. See Usage Note at awhile.
2. The time, effort, or trouble taken in doing something: The project wasn't worth my while.
conj.
1. As long as; during the time that: It was lovely while it lasted.
2. In spite of the fact that; although: While that guitar may look nice, it's not a very good instrument.
3. And on the contrary: The soles are leather, while the uppers are canvas.
tr.v. whiled, whil·ing, whiles
To spend (time) idly or pleasantly: while the hours away.
[Middle English, from Old English hwīl; see kweiə- in the Appendix of Indo-European roots.]
Usage Note: As a conjunction, while is used to indicate that two events are happening at the same time (While I was preparing the hamburger patties, she sliced the onions and tomatoes), but it can also be used to contrast two clauses in a nontemporal way (While the "h" is silent in the word "honest," it is pronounced in the word "hostile"). While has been used in this nontemporal sense for hundreds of years, and the latter sentence was judged acceptable by 75 percent of the Usage Panel in our 2012 survey. The Panel was somewhat less accepting, however, of this use of while in a sentence where it could potentially be misread as having a temporal meaning (31 percent disapproved of the sentence She said she wanted to go to a movie, while he proposed seeing a play). And 43 percent disapproved of a sentence in which the two contrasting clauses are explicitly not simultaneous: While the Tigers beat the Cubs last week, this week the Cubs beat the Tigers. To avoid ambiguity or an unintended suggestion of simultaneity, choose a different conjunction, such as although or whereas.