edgeways
adv.
also edge-ways, "with the edge turned forward or toward a particular point," 1560s, from edge, n. + way, n.. First attested form of the word is edgewaie; the adverbial genitive -s appears by 1640s. Edgewise (1715) appears to be a variant, based on otherwise, etc. See edge, v..
As if it were possible for any of us to slide in a word edgewise! [Mary Mitford, "Our Village," 1824].
To edge in a word in this sense is from 1680s.