[...] roots are not members of lexical categories, but words are.
- Giegerich (2004), Pag. 205

[...] we define Root as a morphological category that has no lexical-category specification and that is bound in the sense that it needs to undergo "at lest" rule (10) [Root-to-Word Conversion] [...].
- Giegerich (2004), Pag. 216

Class-1 affixes attach to both "stems" and words while Class-2 affixes attach to words only [...]. there are two (recursive) category levels or types that play a role in English word structure - Word, along with a "lower" category type, Root - and [...] Class I affixes attach to...categories of type Root (and with them form roots), while Class II affixes attach to categories of type Word (and with them form words) [...].
- Giegerich (2004), Pag. 203

It is clear a characteristic of the category Root that its members do not have to be free forms [...].
- Giegerich (2004), Pag. 204

Root [...] "...that part of a form of a word which remains when all derivational and inflectional affixes have been removed..." [Lyons, John, 1970a, “Morphology”, Lyons, ed. (1970b), p. 325] [...].
- Giegerich (2004), Pag. 205