1. ambiguous, of double or doubtful character ...1644 obs.
2. of language: ambiguous in sense ...1647
from Latin amphibol-us (ambiguous)
(from Greek ἀμϕίβολ-ος (amphíbolos, ambiguous)
FIRST DOCUMENTED USE
1644 - see EXAMPLE below
"...There was never such a confused mysterious civil war as this; there were never so many bodies of strength on sea and shore, never such a choice of arms and artillery, never such a numerous cavalry on both sides, never a greater eagerness and confidence, never such an amphibolous quarrel; both parties declaring themselves for the king, and making use of his name in all their remonstrances to justify their actions..."
From: The Harleian Miscellany: A Collection of Scarce, Curious, and Entertaining Pamphlets and Tracts, as well in Manuscript as in print, found in the late (Edward Harley, second) Earl of Oxford's library;
England's Tears, for the present Wars; which for the Nature of the Quarrel, the Quality of Strength, the Diversity of Battles, Skirmishes, Encounters, and Sieges, happened in so short a Compass of Time, cannot be paralleled by any precedent Age.