To articulate or engage in articulation by moving the lips or other speech organs without making audible sounds, as in reading to oneself.(verb-transitive)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "subvocalize" in a sentence
"Most readers, and precisely because they subvocalize in the production of a text, are likely to be taken momentarily aback by this thumbnail sketch of"
"If you need to speak to the whole group just subvocalize."
"[I] read what I write out loud rather than just subvocalize it as I write."