Words in the mind
There are two places in the mind where it is claimed words are located.
Word in the usual everyday sense is a meta-linguistic concept, WORD (a place in the mind outside the core language system of phonological and syntactic structure) linked directly to perceptual structures. So for example the acoustic structure [kat] can be directly associated with the conceptual structure WORD. The words you are reading now that are separated by spaces correspond to separate units in the mind of which we can be conscious of.
The other place word is located in the mind is as a multi-unit structure that is activated during processing made of a chain of phonological, syntactic and conceptual structure, that we are never conscious of. (Smith & Truscott 2014: 354).
The video below shows this tri-partite nature of lexical items using the example of the suffix -ish:
References
Smith, M. S., & Truscott, J. (2014). The multilingual mind: A modular processing perspective. Cambridge University Press.