According to babycenter.com, by 18 months, most children can speak around a dozen words. An 18-month-old can often also link two words together to form rudimentary sentences, and some also may begin referring to themselves and other people by name.Know More
As pbs.org explains, the number of words an 18-month-old can recognize extends far beyond their spoken vocabulary, with most being able to understand up to 200 or more words. At this age, toddlers also begin to understand the importance of tone and can differentiate between commenting, questioning, positive and negative intonation. However, infants at this age will still tend to have trouble with pronunciation, and unfamiliar adults often cannot understand the child's speech.