1 [count] a : a small, sharp nail usually with a wide, flat head
▪ carpet tacks
b US : thumbtack 2 sailing a [count, noncount] : the direction that a ship or boat is sailing in as it moves at an angle to the direction of the wind
▪ We were sailing on (a/the) port tack. [=with the wind coming from our port/left side] ▪ the starboard tack
b [count] : a change from one direction to another direction while sailing
▪ a tack from port to starboard
c [count] : the distance traveled while sailing in a particular direction
▪ a long tack 3 : a way in which you do something or try to do something [singular] ▪ He thought he should try a new/different tack. [noncount] ▪ The company decided to change tack. [=to try using a different method/approach] 4 [count] : a loose stitch that is used to hold pieces of cloth together before sewing them tightly together