let 2 
(lĕt)
(lĕt)n.
1. Something that hinders; an obstacle: free to investigate without let or hindrance.
2. Sports An invalid stroke in tennis and other net games that requires a replay.
tr.v. let·ted or let, let·ting, lets
Archaic
Archaic
To hinder or obstruct.
[Middle English lette, from letten, to hinder, from Old English lettan; see lē- in the Appendix of Indo-European roots.]