The Collaborative International Dictionary of English v.0.48:

Trusty \Trust"y\, a. [Compar. Trustier; superl. Trustiest.]
   1. Admitting of being safely trusted; justly deserving
      confidence; fit to be confided in; trustworthy; reliable.
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            Your trusty and most valiant servitor. --Shak.
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   2. Hence, not liable to fail; strong; firm.
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            His trusty sword he called to his aid. --Spenser.
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   3. Involving trust; as, a trusty business. [R.] --Shak.
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