"אתרוגים" refers to the plural form "etrogim," meaning multiple citrons, while "אתרוג" refers to the singular form "etrog," meaning one citron. Both terms are used in the context of Sukkot, where the etrog is one of the Four Species used in the ritual observance of the holiday. The etrog is particularly valued for its beauty and quality, and finding a kosher etrog is an important part of the preparations for Sukkot.