Back in elementary school, we all learned the basics rules of orthography — the conventions of writing English that deal with spelling, punctuation, hyphenation, and capitalization. One of the first lessons is the difference between uppercase (the formal term is majuscules) and lowercase letters (minuscules). Incidentally, these terms come to us from the world of metal movable type used by letterpress printing introduced by Johannes Gutenberg in the mid 1400s. When setting movable type, typographers stored the majuscules in a shallow wooden case that was located above the wooden case that held the minuscules. But returning to the subject of capitalization, we also learned about the types of capitalization or case styles, such as sentence case, title case, all caps (or all uppercase), small caps, all lowercase, and mixed case (discussed below).
At some point, corporate America realized that tinkering around with capitalization — moving capitalized letters inside the word — created some memorable company and trademark product names. The audacity! Some of the earliest of these type of unconventionally capitalized words were introduced by pioneering companies in the early to mid 1900s: DryIce Corporation (1925); CinemaScope (1953); AstroTurf (1967). It took several decades for the geniuses in the advertising industry to realize the power of the clever capitalization of words — especially since they were running out of traditional names plucked out of dictionaries. Beginning in the 1980s and culminating in the 20o0s, high-tech companies began introducing unusual company and trademarked product names at a rapid pace (i.e., QuarkXPress, iMac, iPhone, eBay, FedEx, NeXT, PlayStation, YouTube). They certainly didn’t teach us about this use of capitals in grammar school — inviting the question: “so what do you call a word that has capitals in the middle?”
Capital question. The formal orthographical term is medial capital (or plural, medial capitals) or bicapitalization — defined as a capital letter occurring in the middle or inside of the word. Interestingly, medial capitals have many synonyms, considered informal terms: bicaps (shortened form bicapitalization), CamelCase, embedded caps, InterCaps (shortened form of internal capitalization, introduced in 1990s by Ave Rappoport), midcaps (shortened form of middle capitals). In 2005, lexicographer Charles Harrington Elster proposed the term CorpoNym for company or brand names with medial capitals (eg, ExxonMobil, HarperCollins, ConAgra).
CamelCase comes from the world of programming. In his book, The Wikipedia Revolution, Andrew Lih describes how early programmers struggled with CamelCase in the early days of developing pages for Wikipedia. The term, named after the humps of capital letters similar to those of a Bactrian camel, was introduced by Newton Love in 1995. He wrote on USENET: “With the advent of programming languages having these sorts of constructs, the humpiness of the style made me call it HumpyCase at first, before I settled on CamelCase.” And you can bet that programmers, with a penchant for developing clever jargon have MANY synonyms for CamelCase, including: BumpyCaps, BumpyCase, NerdCaps, CapWords, compoundNames, Embedded Caps, HumpintheMiddle word, HumpBack notation, InterCapping, mixedCase, Pascal case, Smalltalk case, WikiWord, WikiCase, and ProperCase.
Mixed case or mixed capitalization (also known as StUdLyCaPs or just studlycaps) is distinct from intermediate capitals because capitalization is completely random or follows a simple rule (eg, only vowels are capitalized; every other letter is capitalized). Passwords that contain random uppercase and lowercase letters are example of mixed case words.
For further reading: The Wikipedia Revolution by Andre Lih
What in the Word?: Wordplay, Word Lore, and Answers to the Peskiest Questions About Language by Charles Harrington Elster