Sign languages are complete, natural languages with their own grammar — they are not universal and vary by country.

Language diversity correlates with biodiversity — the same conditions that support species richness also support linguistic richness.

The word 'nice' originally meant foolish or stupid in 13th-century English — its meaning has almost fully reversed.

All human languages have nouns and verbs — but many lack adjectives or other categories found in English.

The word 'goodbye' is a contraction of 'God be with ye.'

The longest word in English, pneumonoultramicroscopicsilicovolcanoconiosis, was invented to be the longest word.

Code-switching — alternating between two languages mid-sentence — is a sophisticated skill, not a deficiency.

Noam Chomsky proposed humans have an innate 'universal grammar' — a built-in capacity for language.

The word 'set' has over 430 definitions in some English dictionaries — the most of any word.