The plural of the noun emphasis is emphases. Tired students can write
emphasises as the plural of 'an emphasis'. This is a mistake. Emphasis is one of a group of words whose use and spelling can mislead readers, particularly those for whom English is a second language. Spellcheckers can sometimes allow wrong word choices to stand in a draft, so be warned.
- Emphasis (pronounced 'EM-fer-sis' IPA: /'ɛmfəsɪs/} is a noun. This is its singular form - it ends in '-s-' because it is derived from a foreign language, in this case from Greek through Latin. In Latin, its plural form is emphases, which remains the standard plural in written English. The singular and the plural sound quite similar in informal English, so if you want to make it clear that you mean the plural, for example in an academic seminar or lecture, it is usual to give extra stress to the final vowel, making it a strong '-ee-' (IPA: /i:/) sound, 'emf-er-SEEZ' (IPA: /ɛm fə 'siːz/), where in less careful speech, it is realized more as 'EM-fer-seez', IPA: /ˈɛm fə siz/.
- The verb has a different vowel sound in the final syllable, an 'eye' (IPA: /aɪ/) sound. This is shown by the final letter '-e-': emphasise, 'EM-fer-size' (IPA: /'ɛm fə saɪz/), with a regularly formed third person singular in the present tense of emphasises IPA: /'ɛm fə 'saɪz ɪz/. Careless typing of an -e- or an -i- or even an -s- in this part of the word is what your spellchecker will sometimes allow, accepting your use of a noun instead of a verb, or vice versa.
- The word emphasises is a form of the verb only.
This is one of the 117 mis-spellings listed as 'Common difficulties' in the section on 'Spelling' within 'Writing' in UEfAP.