What does capitalisation mean?
Capitalisation refers primarily to the use of capital letters in written language — starting sentences with capitals, marking proper nouns such as people's names, cities, and organisations, and signalling titles or headings. The word carries a second, entirely distinct meaning in finance: market capitalisation describes the combined value of a company's outstanding shares, calculated by multiplying share price by share count. It is a formal, technical term in both domains, appearing most often in style guides, editorial discussions, and financial reporting. Spelled with -s- in British and Commonwealth English, it takes a -z- in American usage, though the meaning is unchanged. Understanding both senses matters: poor capitalisation in prose signals carelessness to editors, while shifts in a firm's capitalisation can indicate major changes in how investors value it.
The action or convention of using capital letters in writing.
"The capitalisation of place names varies considerably across European languages."
The total value of a company's outstanding shares (market capitalisation).
"Apple's market capitalisation exceeded three trillion dollars."
Rarely pluralised except in financial contexts where multiple valuations are compared.
"The report compared the capitalisations of several mid-cap firms."
Every company listed on the London Stock Exchange has a 'market capitalisation' — a figure that can swing by billions overnight without a single letter changing case.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of capitalisation
Capitalisation derives from 'capital', which comes from Latin 'capitalis' ('of the head'), itself from 'caput' ('head'). The Latin root also gives us words like capitulate and decapitate. The verb 'capitalise' emerged in the early modern period, and the noun form developed alongside it, gaining its financial sense during the growth of joint-stock companies in the eighteenth and nineteenth centuries.
Related word forms
How capitalisation is actually used
This spelling is standard in British English and other Commonwealth varieties. American English uses the -z- form exclusively. In finance, 'market capitalisation' is frequently abbreviated as 'market cap'.
Easily confused with capitalisation
Capitalisation with an -s- is the standard British spelling, while capitalization with a -z- is the standard US spelling; the meaning is identical.