worthwhile

Multiple Entries:
  worthwhile    while  

Concise Oxford English Dictionary © 2008 Oxford University Press:
worthwhile/wɜːθˈwʌɪl/

▶adjective worth the time, money, or effort spent.

– derivatives
worthwhileness noun.

usage: When worthwhile is used attributively (i.e. before the noun) it is always written as one word: a worthwhile cause. However, when it is used predicatively (i.e. it stands alone and comes after the verb) it may be written as either one or two words: we didn't think it was worthwhile or worth while.

Concise Oxford English Dictionary © 2008 Oxford University Press:
while/wʌɪl/

▶noun

• 1 (a while) a period of time.

  ■ for some time.

• 2 (the while) at the same time; meanwhile.

  ■ literary during the time that.

▶conjunction

• 1 at the same time as.

• 2 whereas (indicating a contrast).

  ■ although.

▶relative adverb during which. ▶verb (while time away) pass time in a leisurely manner. ▶preposition N. English until.

– phrases
worth while (or worth one's while) worth the time or effort spent.

– origin OE hwīl ‘period of time’, of Gmc origin; the conjunction is an abbrev. of OE thā hwīle the ‘the while that’.

usage: On the distinction between worth while and worthwhile, see usage at worthwhile.