godan verb (-su), transitive verb
Rare, somewhat old-fashioned or literary verb for understanding. In modern Japanese, わかる or 理解する are far more common. The potential form 解せる (げせる) is also used.
See also: 解せる
彼の言うことはどうも解せない。
I just can't understand what he says.
その言葉の真意を解するのは難しい。
It is difficult to comprehend the true meaning of those words.