The original example of skeleton and Wellington, and most of the others mentioned would be described in poetry as half rhymes or near rhymes. eg cat/cot, hat/bag.End consonants may have the same sound or the internal vowels may have the same sound. Tough/bough are eye rhymes. As a poet, I like pushing the bounaries back, and find that half rhymes allow you the scope to be unpredictable, and are a device that permits playfulness with language without the forced constraints of full rhymes.
My personal favourite half rhymes for orange are strange, porridge, and, best of all, Boris.
Half rhymes for silver include sliver, slavver, cleaver and whisper.