Do you have a knack for writing?

Or is it all a trick?

A knack, the linguist Robert Beard writes, is a special, inexplicable skill or talent for carrying out a specific action.

That's the noun. There are other forms, he says, of which I have not been familiar.

The verb knack means "to crack, to make the noise of cracking," reflecting the original meaning of knack, the noun. Knacker "something that makes a sharp cracking sound," bears the same meaning. Knick-knack once meant "clatter," the alternation of knicking and knacking sounds. It followed the noun knack to its second historical meaning, "a trick" before ending up with its current sense, "a trinket, gimcrack, kickshaw."

Well, I knew knick-knack. I've never heard of kickshaw.

Knack has a long and curious past, the good doctor informs. It started out around 1380 meaning a cracking sound. This is confirmed by its cousins in other Germanic languages, knacken "to crack" and Norwegian knake "crack." (We also find Gaelic cnac with the same meaning.) For some unknown reason, by the time it reached the middle of the 16th century that meaning had given way to "deception, trick." Probably along the lines of crack shifting its meaning to "snide remark." The sense of "special talent" was first recorded in the 1580s, showing that "trick" took little time to be interpreted as a "special talent."

Knack, I'm going to suggest, is "woody."