Gospel Topics essay defines chastity as "not having any sexual relations before marriage."
"Chastity," Gospel Topics, The Church of Jesus Christ of Latter-day Saints; accessed Sept. 20, 2021
Chastity means not having any sexual relations before marriage. It also means complete fidelity to husband or wife during marriage.
. . . All sexual relations outside of marriage violate the law of chastity and are physically and spiritually dangerous for those who engage in them.