trebly

From treble +‎ -ly.

trebly (comparative treblier or more trebly, superlative trebliest or most trebly)

1. Having treble, or high-pitched, qualities.
   • 2024, Scott Alexander Howard, The Other Valley, Atlantic Books (2025), page 162:

     With the room so bare, Ivret’s voice sounded different, trebly echoes ringing off her sibilants.

trebly (not comparable)

1. (archaic) Three times, thrice
2. To three times the extent or degree; triply.
   • 1883, Robert Louis Stevenson, Treasure Island, Cignet Classic, published 1998, page 13:

     For my part, I must do my best to save this fellow's trebly worthless life; Jim, you get me a basin.

• (three times): thricely, threefold; see also Thesaurus:thrice