1. extra extra small - Noun
2. extra extra small - Adjective
(countable) An item labelled or denoted as being that size.
(countable) One who fits an item of that size.
Used other than figuratively or idiomatically: see extra, small.
(uncountable) One of several sizes to which an item may be manufactured.
Synonym: XXS
(especially clothing) That is extra extra small (the manufactured size).
Source: en.wiktionary.org