tack

Middle English takke meant a clasp, fastener, or small nail — from Old North French taque, itself from a Germanic source. By the 1400s, sailors used tack to name the rope that held the lower windward corner of a sail. The corner itself became known as the tack. Then the side of the boat that the tack was on became the tack. Then the act of changing sides became tacking. Each shift was logical; the accumulated drift was enormous.

Tacking is the fundamental maneuver of upwind sailing. Because a sailboat cannot sail directly into the wind, it must zigzag — sailing at an angle to the wind on one tack, then turning the bow through the wind to sail at an angle on the other tack. The zigzag path covers more distance than a straight line but gets you where a straight line cannot.

By the 1600s, the metaphor had moved ashore. To 'take a different tack' meant to change your approach to a problem. Samuel Johnson used it. So did politicians, generals, and diplomats. The metaphor carried perfectly: sometimes the direct path is impossible, and the only way forward is an angled one.

Modern English uses tack in dozens of contexts — thumbtacks, carpet tacks, taking a new tack in negotiations, tacking a notice to a board. The nail and the sail maneuver coexist in the same word, connected by the thread of fastening and direction. A small nail holds the corner of a sail. The corner names a direction. The direction names a strategy.