From The Collaborative International Dictionary of English v.0.48:
Sley \Sley\, n. [AS. sl?, fr. sle['a]n to strike. See Slay, v.
t.]
1. A weaver's reed. [Spelt also slaie.]
[1913 Webster]
2. A guideway in a knitting machine. --Knight.
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3. (Weaving) The number of ends per inch in the cloth,
provided each dent in the reed in which it was made
contained an equal number of ends. --E. Whitworth.
[Webster 1913 Suppl.]
From The Collaborative International Dictionary of English v.0.48:
Sley \Sley\, v. t.
To separate or part the threads of, and arrange them in a
reed; -- a term used by weavers. See Sleave, and Sleid.
[1913 Webster]