Rig Veda I.114.5 (dedicated to Rudra) says
दि॒वो व॑रा॒हम॑रु॒षं क॑प॒र्दिनं॑ त्वे॒षं रू॒पं नम॑सा॒ नि ह्व॑यामहे । हस्ते॒ बिभ्र॑द् भेष॒जा वार्या॑णि॒ शर्म॒ वर्म॑ च्छ॒र्दिर॒स्मभ्यं॑ यंसत् ॥५॥
We call down with reverence the boar of heaven, flame-red, with braided hair, turbulent in form. Bearing in his hand desirable healing remedies, he will extend shelter, covering, and protection to us.
In Puranas it was used to indicate the incarnation of Vishnu.
My question is - Why was the epithet varAha (वराह) used for Rudra in Rig Veda I.114.5?
In the mantra व॑रा॒हम॑रु॒षं Can be split into varAham + aruSa . aruSa indicates shape of a varAha.