Both Uses of

inarticulate

in

Lord of the Flies

"We could be sort of…" Simon became inarticulate in his effort to express mankind's essential illness.
p. 89.4 *

inarticulate = at a loss for words

Then the wail rose, remote and unearthly, and turned to an inarticulate gibbering.
p. 94.8

inarticulate = without words

Definition:

unable to communicate clearly (or to use words)

or (more rarely): a feeling or idea that is not expressed

The exact meaning of inarticulate depends upon its context. For example:

unable to find good words to express oneself -- as in "She gets inarticulate when she's nervous."
verbally expressing a feeling without words -- as in "She uttered an inarticulate cry of despair."
unable to make oneself heard and understood -- as in "She mumbled inarticulately."
unable to speak -- as in "She was inarticulate with rage."
a feeling or idea that is not expressed -- as in "We shared an inarticulate fear."
inability to express or understand feelings or ideas -- as in "She is emotionally inarticulate, " or "Her symphony is inarticulate."