Chaste, pure, modest, decent are comparable when they mean free from all taint of what is lewd or salacious.
Chaste fundamentally implies an opposition to immoral in the sense of that word in which it connotes lustfulness and licentiousness. The term therefore suggests a refraining from all acts or thoughts that incite desire or are not in accordance with virginity or marriage vows.
It particularly stresses restraint and an avoidance of anything thought to defile or make unclean not only the love of man and woman but whatever should be free from cheapness, debasement, or vulgarization.
Pure differs from chaste mainly in its suggestion of freedom from all taint of evil thought or immoral desires; it implies innocence and absence of temptation rather than, as chaste implies, control over one’s impulses and actions.
Modest and decent are frequent in this sense as applied especially to behavior and to dress as outward manifestations of an inward chastity or purity. Modest usually also implies an absence of brazenness, boldness, or other characteristics unbefitting one who is by nature chaste or pure; decent, a due concern for what is regarded as seemly or proper (see also DECOROUS).