Isotopes are versions of an element; for example, Carbon - 13 has an extra neutron and is a more massive version of the common Carbon - 12. (sciencedaily.com)
Smaller sized overriders were to be found on the bumpers - though for export to the U.S.A. as well as for some coachbuilt cars the previously used more massive version was retained. (rrab.com)
NESSI will focus on about 100 exoplanets, ranging from massive versions of Earth, called super-Earths, to scorching gas giants known as «hot Jupiters.» (sciencedaily.com)