Pirouette a la seconde is a classical ballet term meaning a “spin with leg to the side” or “spin with leg in second position.” A dancing performing a pirouette a la seconde will be turning on their supporting leg with their other leg to the side and straight with a pointed foot. It can be done en dehors or en dedans, or with a plié between repeating, multiple turns.
There are a couple different versions of pirouette a la seconde:
A dancer may do a pirouette a la second en dedans in an adagio. This is commonly seen in a performance, where the double pirouette a la seconde en dedans is performed by the ballerina (as Kitri) in the wedding pas de deux from Don Quixote where the male dancer (as Basilio) comes in at the last moment to partner her into a penché.
Pirouette a la seconde en dehors is the proper way to say “a la seconde turns” which usually means single or double a la seconde turns done multiple times with a single plie between each one. This is most commonly seen performed by male dancers in codas of pas de deuxes.