Hairpin turns are a type of sharp turn in a road or path that resembles a hairpin. They are characterized by a tight 180-degree turn, often with a steep incline or decline. The term 'hairpin turn' is derived from the resemblance of the turn to a hairpin or bobby pin. Hairpin turns are often used in mountain roads and race tracks to slow down drivers and increase the difficulty of the course. The crossword solution for hairpin turns is 'esses, ' which is an abbreviation for the word 'excesses.'