monosyllabism
/ˌmɒnə(ʊ)ˈsɪləbɪz(ə)m/noun
1The property or fact of being either wholly or predominantly monosyllabic; the use of monosyllables.
2 Linguistics. The property of a language of having only or predominantly words of one syllable.
Origin
Early 19th century; earliest use found in William Mitford (1744–1827), historian of ancient Greece. From monosyllab- + -ism.