"Praxis" means planned movement. Apraxia is a common feature of a stroke or brain injury affecting the parietal lobe of the brain. It is an inability to perform a learned motor task or behavior. For example, a stroke survivor may be capable of picking up a comb, naming it, and telling you what it is. However, he is unable to carry out the sequence of movements which are necessary to use the comb on his hair.
From a speech and language standpoint patients with apraxia have difficulty planning and producing the precise, specific series of movements of the tongue, lips, jaw and palate that are necessary for intelligible speech.