the GNU version of the Collaborative International Dictionary of English
adj. Capable of being surmised.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. capable of being inferred on slight grounds
Word Usage
"I found myself in a long road of tall and unlit mansions, stretching away into the distance, its length surmisable alone by the thread of twinkling gas-lamps which lay in front."