word-forming element meaning "miniature, minor," abstracted from miniature, with sense perhaps influenced by minimum. The vogue for mini- as a prefix in English word coinage dates from c. 1960; minicam for "miniature camera" (1937) is an early use.
1610s, "a number or set of things of one kind arranged in a line, a continued succession of similar things," also of events following in order, from Latin series "row, chain, series, sequence, succession," from serere "to join, link, bind together, arrange, attach, put; join in speech, discuss" (from PIE root *ser- (2) "to line up"). The earlier word was serie "sequence of thoughts, discussion of a subject" (late 14c.).
The meaning "set of printed works published consecutively and having something in common" is from 1711. The meaning "set of radio or television programs with the same characters and themes" is attested from 1949. The baseball sense of "set of games on consecutive days between the same teams" is from 1862.
<a href="https://www.etymonline.com/word/mini-series">Etymology of mini-series by etymonline</a>
Harper, D. (n.d.). Etymology of mini-series. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/mini-series