Frum
Frum (Yiddish: פֿרום; [frum | frim], related to German fromm), meaning devout or pious, is a Yiddish describing word. To be frum means to be committed to the observance of Jewish religious law that often exceeds the bare requirements of Halakha, the collective body of Jewish religious laws. This not only includes the careful study of Torah, daily prayers, observing Shabbat and kashrut, and performing deeds of loving-kindness but also many more customs and khumrot. Khumrot are prohibitions or obligations in Jewish life that exceed the requirements of Halakha, some khumrot became customs in some communities over time, e.g. daily ritual immersion in a mikveh in Hasidic or kapparot in Haredi Judaism.
Someone who is frum or devout is known as a frum Jew, a frummer (Yiddish "pious one", related to a German noun "ein Frommer") or frummie (Yinglish diminutive "pious one"). These appellations are generally, but not only, applied to Hasidic and Orthodox Judaism, and used by some members of these groups as a self-reference.