From The Collaborative International Dictionary of English v.0.48:
Knack \Knack\ (n[a^]k), v. i. [Prob. of imitative origin; cf. G.
knacken to break, Dan. knage to crack, and E. knock.]
1. To crack; to make a sharp, abrupt noise to chink. [Obs. or
Prov. Eng.] --Bp. Hall.
[1913 Webster]
2. To speak affectedly. [Prov. Eng.] --Halliwell.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.48:
Knack \Knack\, n.
1. A petty contrivance; a toy; a plaything; a knickknack.
[1913 Webster]
A knack, a toy, a trick, a baby's cap. --Shak.
[1913 Webster]
2. A readiness in performance; aptness at doing a specific
task; skill; aptitude; facility; dexterity; -- often used
with for; as, a knack for playing the guitar.
[1913 Webster +PJC]
The fellow . . . has not the knack with his shears.
--B. Jonson.
[1913 Webster]
The dean was famous in his time,
And had a kind of knack at rhyme. --Swift.
[1913 Webster]
3. Something performed, or to be done, requiring aptness and
dexterity; a trick; a device. "The knacks of japers."
--Chaucer.
[1913 Webster]
For how should equal colors do the knack ! --Pope.
[1913 Webster]