From Middle English swiftly, swyftely, swiftliche, from Old English swiftlīċe (“swiftly”), equivalent to swift + -ly.
swiftly (comparative swiftlier or more swiftly, superlative swiftliest or most swiftly)
- In a swift manner; quickly; with quick motion or velocity; fleetly
2011 September 2, Phil McNulty, “Bulgaria 0-3 England”, in BBC:
Gary Cahill, a target for Arsenal and Tottenham before the transfer window closed, put England ahead early on and Rooney was on target twice before the interval as the early hostility of the Bulgarian supporters was swiftly subdued.