Direct and indirect evidence of compression of word lengths. Zipf’s law of abbreviation revisited

Zipf’s law of abbreviation, the tendency more frequent words to be shorter, is one most solid candidates for a linguistic universal, in sense that it has potential being exceptionless or with number exceptions vanishingly small compared languages on Earth. Since pioneering research, this been viewed as manifestation universal principle communication, i.e. minimization word lengths, reduce effort communication. Here we revisit concordance written language abbreviation. Crucially, provide wider evidence holds also speech (when length measured time), particular 46 from 14 families. Agreement abbreviation provides indirect compression via theoretical argument prediction optimal coding. Motivated by need direct compression, derive simple formula random baseline indicating lengths are systematically below chance, across families and writing systems, independently unit measurement (length characters duration time). Our work paves way measure compare degree optimality languages.