Both Uses of

manifold
in
King Lear

Persuade me to the murder of your lordship; But that I told him the revenging gods 'Gainst parricides did all their thunders bend; Spoke with how manifold and strong a bond The child was bound to the father;—sir, in fine, Seeing how loathly opposite I stood To his unnatural purpose, in fell motion With his prepared sword, he charges home My unprovided body, lanc'd mine arm; But when he saw my best alarum'd spirits, Bold in the quarrel's right, rous'd to the encounter, Or whether gasted by the noise I made, Full suddenly he fled.†
Scene 2.1 *

manifold = many and varied

'If any man of quality or degree within the lists of the army will maintain upon Edmund, supposed Earl of Gloster, that he is a manifold traitor, let him appear by the third sound of the trumpet.†
Scene 5.2

Definitions:

(1) (manifold as in: reasons are manifold)
many and varied
(2) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

Manifold can also be used as a noun to refer to a pipe that has several lateral outlets to or from other pipes; such as "the intake manifold of an engine." A comprehensive dictionary will contain other, more specialized, meanings.