Is it ensure, insure, or assure?
Old English storc, related to stear "stiff, strong" (see stark), from Proto-Germanic *sturkaz (cf. Old Norse storkr, Middle Dutch storc, Old High German storah, German Storch "stork"). Perhaps so called with reference to the bird's stiff or rigid posture. But some connect the word to Greek torgos "vulture."
Old Church Slavonic struku, Russian sterch, Lithuanian starkus, Magyar eszterag, Albanian sterkjok "stork" are Germanic loan-words. The fable that babies are brought by storks is from German and Dutch nursery stories, no doubt from the notion that storks nesting on one's roof meant good luck, often in the form of family happiness.
Heb. hasidah, meaning "kindness," indicating thus the character of the bird, which is noted for its affection for its young. It is in the list of birds forbidden to be eaten by the Levitical law (Lev. 11:19; Deut. 14:18). It is like the crane, but larger in size. Two species are found in Palestine, the white, which are dispersed in pairs over the whole country; and the black, which live in marshy places and in great flocks. They migrate to Palestine periodically (about the 22nd of March). Jeremiah alludes to this (Jer. 8:7). At the appointed time they return with unerring sagacity to their old haunts, and re-occupy their old nests. "There is a well-authenticated account of the devotion of a stork which, at the burning of the town of Delft, after repeated and unsuccessful attempts to carry off her young, chose rather to remain and perish with them than leave them to their fate. Well might the Romans call it the pia avis!" In Job 39:13 (A.V.), instead of the expression "or wings and feathers unto the ostrich" (marg., "the feathers of the stork and ostrich"), the Revised Version has "are her pinions and feathers kindly" (marg., instead of "kindly," reads "like the stork's"). The object of this somewhat obscure verse seems to be to point out a contrast between the stork, as distinguished for her affection for her young, and the ostrich, as distinguished for her indifference. Zechariah (5:9) alludes to the beauty and power of the stork's wings.