Definitions:
a number of events, objects, or people of a similar or related kind coming one after another

a set or sequence of related television or radio programmes

denoting electrical circuits or components arranged so that the current passes through each successively

(in chronostratigraphy) a range of strata corresponding to an epoch in time, being a subdivision of a system and itself subdivided into stages

a set of elements with common properties or of compounds related in composition or structure

a set of quantities constituting a progression or having the several values determined by a common relation.

a group of speech sounds having at least one phonetic feature in common but distinguished in other respects