Use the adjective inarticulate to describe poor communication skills, like at your most inarticulate moments when you nervously fumble to find the right word and completely forget to make your most important point.
Inarticulate sounds — a grunt, cry, scream, snort, wail, howl, moan, sob, snicker — are heard but not easily understood. If something is inarticulate, it is hard to get the meaning, like an inarticulate speech whose main idea can't be found. Creative works can also be inarticulate, when it isn't clear what — if anything — they are trying to express, like a painter whose gallery show that is called "inarticulate" by a critic: You can't grasp what the artist is trying to say.
