2) elastomer. The Columbia Encyclopedia, Sixth Edition. 2001
...elastomer, (ilas´tmr) (KEY) , substance having to some extent the elastic properties of natural rubber. The term is sometimes used technically to distinguish synthetic...

3) elasmobranch. The Columbia Encyclopedia, Sixth Edition. 2001
...Elasmobranchii of the vertebrate class Chondrichthyes (see Chordata). This group includes sharks, skates, and rays....

4) instrument-landing system. The Columbia Encyclopedia, Sixth Edition. 2001
...The pilot flies his aircraft along a course delineated by the intersection of two radio beams-the localizer beam for guidance in the horizontal plane and the glide-slope...