α. Old English fiftegða, Old English fifteið- (Northumbrian, inflected form), Old English fifteodan (inflected form, probably transmission error), Old English fifteogeþa, Old English fifteogeða, Old English fifteogþa, Old English fifteogða, Old English fifteoða, Old English fifteða, Old English fyfteoða, Old English–early Middle English fifteoþa, early Middle English fifteode, early Middle English fifteoðe, Middle English fifteþe, Middle English fyfteþe (perhaps transmission error), Middle English vifteþe; N.E.D. (1896) also records a form early Middle English vyfteoþe.
β. Middle English fifetende, Middle English fiftend, Middle English fiftende, Middle English fijftend, Middle English fyftend, Middle English fyftende, 1500s vifftend (Kent).
γ. early Middle English fiftenðe, Middle English ffiftenþe, Middle English ffyfftenþe, Middle English fifteenþe, Middle English fiftenþe, Middle English fiftynþe, Middle English fyftenethe, Middle English fyfteneþe, Middle English–1500s fifteneth, Middle English–1500s fiftenthe, Middle English–1500s fyfteneth, Middle English–1500s fyftenth, Middle English–1500s fyftenthe, Middle English–1600s fyfteenth, 1500s fifteenthe, 1500s fiftenethe, 1500s fiuetenth, 1500s fyuetenth, 1500s fyuetenthe, 1500s–1600s fiueteenth, 1500s–1700s fifteeneth, 1500s–1700s fiftenth, 1500s– fifteenth, 1600s fiveteenth, 1600s fivetenth; Scottish pre-1700 fiftinth, pre-1700 fiftinthe, pre-1700 fyfteinth, pre-1700 fyftinth, pre-1700 fyftinthe.
δ. Scottish pre-1700 fifteint, pre-1700 fiftent, pre-1700 fiftente, pre-1700 fyfteint, pre-1700 fyftent, pre-1700 fyifteint.
Also represented by the abbreviations 15th, 15th, xvth, xvth, XVth, XVth, and variants.