Source : Webster's Revised Unabridged Dictionary (1913)

Trusty \Trust"y\, a. [Compar. {Trustier}; superl. {Trustiest}.]
   1. Admitting of being safely trusted; justly deserving
      confidence; fit to be confided in; trustworthy; reliable.

            Your trusty and most valiant servitor. --Shak.

   2. Hence, not liable to fail; strong; firm.

            His trusty sword he called to his aid. --Spenser.

   3. Involving trust; as, a trusty business. [R.] --Shak.

Source : WordNet®

trusty
     adj : worthy of trust or belief; "a trustworthy report"; "an
           experienced and trustworthy traveling companion" [syn:
           {trustworthy}] [ant: {untrustworthy}]
     [also: {trustiest}, {trustier}]

trustiest
     See {trusty}