Etymology
http://en.wiktionary.org/wiki/let#Etymology_1
Etymology 2
Middle English letten (“to hinder, delay”) from Old English lettan (“to hinder, delay"; literally, "to make late”), from Proto-Germanic *latjanan. Akin to Old English latian (“to delay”), Dutch letten, Old English læt (“late”). More at late, delay.
[edit]Verb
let (third-person singular simple present lets, present participle letting, simple past letted, past participle let)
(archaic) To hinder, prevent.
[edit]Noun
let (plural lets)
A hindrance.
...without let or hindrance (on all commonwealth passports)
(tennis) The hindrance caused by the net during serve, only if the ball falls legally.
