Language Arts St Robert’s Newtown


Every word is a base. Some are free-standing, some are bound. On that base you can either add morphemes (alterable base), or you can’t (unalterable base).

Here are some free-standing alterable bases with their bases altered:

play       playful            played            playing           replaying

help      helpful            helped           helping           unhelpful

do          undo                redo

tie          tied                  untie


Here are some free-standing unalterable bases






Some bases are freestanding, some are not. Here are some bound bases (all bound bases are alterable):

-ject-                 inject                subject             adjective

-struct-            instruct           obstruct          construct

-tract-              subtract           abstract          tractor

-spect-             inspect             spectacle       aspect


Alterable, unalterable, free or bound, a word contains one base, bare minimum. It sometimes contains more than one base, but more about that in compounds.

With practice, you can learn to identify the base in any word. Fortunately, you are not on your own. Various etymological dictionaries will help you isolate and teach bases. Once you get used to doing it, it becomes very hard to suppress this knowledge when studying words.



The Language Arts approach encourages word study that covers bases, their meanings, their families, and the way their spellings are altered when attaching affixes.

Course Navigation

Bases Exercise 1

Lyn Stone

Point out the base in the following words: following, rerun, mislead, inflame, unhappy, doing, return, nonsense, car, interview. Are they free or bound?

Bases Exercise 2

Lyn Stone

Point out the bases in the following words: inject, obstruct, consider, science. Are they free or bound? You may want to use a dictionary for these.