susceptible to debate, challenge, or doubt; questionable: Whether this is the best plan of action or not is arguable.
susceptible to being supported by convincing or persuasive argument: Admirers agree that it is arguable he is the finest pianist of his generation.
Origin of arguable
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
capable of being disputed; doubtful
capable of being supported by argument; plausible
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Online Etymology Dictionary, © 2010 Douglas Harper