The word "Semitontine" is not commonly used, however it is spelled in accordance to the International Phonetic Alphabet (IPA). The word is broken down into four syllables: "se" "mi" "ton" "tine". The initial "s" sound is pronounced as /s/, while the "e" is pronounced as /ɛ/ and the "i" is pronounced as /ɪ/. The second syllable "mi" is pronounced as /mi/, the third syllable "ton" is pronounced as /tɒn/, and the final syllable "tine" is pronounce as /taɪn/.
A form of insurance in which the insured allows all the profits on his policy, from compound interest, lapses, etc., to accumulate for a number of years and then receives the whole amount in a dividend; the beneficiaries of those who die during the period receive the face value of their policies, but the interest in the profits is forfeited to the survivors.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.