פירוש על שמות 2:8

ותלך העלמה AND THE YOUNG WOMAN WENT — she went eagerly and with vigour (עלמות) like a young man (עלם) (cf. Sotah 12b).

ותלך העלמה, “the young lady went, etc.” The reason why the Torah calls her by the description עלמה, is because she concealed the fact that she was the baby’s sister.