Definition of "causeless"

[H]e […] by his overcarefulneſſe and cauſeleſſe ſuſpicion, deprived himſelf of this benefit, and implunged himſelf in much juſt hatred for his unjuſt dealing and treachery.

1639, Thomas Fuller, “The Pilgrimes Arrivall at Constantinople, Entertainment, and Departure”, in The Historie of the Holy Warre, Cambridge, Cambridgeshire: […] Thomas Buck, one of the printers to the Universitie of Cambridge [and sold by John Williams, London], book I, pages 22–23

Alas my fears are cauſless, and ungrounded, / Fantaſtick dreams, and melancholick fumes / Of crazy ſtomacks, and diſtempered brains: / Has this convinc'd you?

1641 (first performance), [John Denham], The Sophy. […], 2nd edition, London: […] J[ohn] M[acock] for H[enry] Herringman, […], published 1667, Act III, page 36