knack

Etymology

Use as "special skill" from 1580. Possibly from 14th century Middle English krak (“a sharp blow”), knakke, knakken, from Middle Low German, by onomatopoeia. Latter cognate to German knacken (“to crack”). See also crack.

noun

1. A readiness in performance; aptness at doing something.
   These men had some uncanny knack of knowing when the steel was right, and like many such things, it just could not be put into a textbook on the subject. 1945 January and February, A Former Pupil, “Some memories of Crewe Works—III”, in Railway Magazine, page 14
   The sophist runs for cover to the darkness of what is not and attaches himself to it by some knack of his; 2005, Plato, translated by Lesley Brown, Sophist, page 254a
   And the Premier League's all-time top-goalscoring midfielder proved he has not lost the knack of being in the right place at the right time with a trio of clinical finishes. October 2, 2011, Jonathan Jurejko, “Bolton 1–5 Chelsea”, in BBC Sport
2. A petty contrivance; a toy.
3. Something performed, or to be done, requiring aptness and dexterity.

verb

1. (obsolete, UK, dialect) To crack; to make a sharp, abrupt noise; to chink.
   If they hear the Beads knack upon each other, that's enough. 1674, Joseph Hall, Bishop Hall's sayings concerning travellers to prevent popish and debauch'd principles, William Miller
2. To speak affectedly.