The word 'tatty' emerged in British English during the early 20th century, evolving from the earlier noun 'tat'. 'Tat' itself, first recorded in the 19th century, likely originates from a dialectal term for a rag or a tattered piece of cloth, possibly influenced by the verb 'to tatter'. The core concept is one of fraying, disintegration, and poor quality. By adding the common English adjectival suffix '-y', meaning "characterized by or full of," the noun transformed into an adjective describing something that is worn-out, shabby, or cheaply made. Its journey reflects a straightforward morphological process where a colloquial term for a ragged object became a standard descriptor for anything dilapidated or tawdry.

The word 'tatty' is a simplex word. It is derived from the noun 'tat', meaning a ragged or shabby person or thing, with the addition of the adjectival suffix '-y'. The origin of 'tat' is uncertain but may be related to the dialectal word 'tatter'.