also: くおうるに
conjunction
besides; furthermore; in addition
Literary conjunction used to add information, similar to その上 or さらに but with a formal, written tone. Often appears in classical or highly formal modern prose.
彼は有能な学者である。加うるに、優れた教育者でもある。
He is a capable scholar. Furthermore, he is also an excellent educator.
Common, neutral conjunction for 'furthermore' or 'in addition'; 加うるに is much more literary and formal.
Everyday spoken and written conjunction meaning 'on top of that'; 加うるに is restricted to formal or literary contexts.
From the classical Japanese verb 加ふ (くわう, 'to add') in its attributive form 加うる plus the particle に, literally 'in addition to adding'. The modern reading くわうるに reflects historical kana usage.