from The American Heritage® Dictionary of the English Language, 4th Edition
- adv. Archaic Soon afterward; presently.
- adv. Archaic Once again.
From Middle English eftsone, from Old English eftsōna : eft, again; see apo- in Indo-European roots + sōna, soon.(American Heritage® Dictionary of the English Language, Fourth Edition)
From eft (“again, after”) + soon + -s (“adverb suffix”) – both senses (“soon after”, “again”) derive from senses of eft, which is related to after. (Wiktionary)