NEAP, a word only used of tides in which the high-water mark is at its lowest, there being the least difference in level between high and low water, opposed to "spring tides" (see TIDE). The word is obscure in origin. It appears in O. Eng. in ntpflod, and only once alone in the expression forthganges nep, " without power of advancing." It may possibly be connected with " nip," in the sense of " pinched," " scanty."
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)