“Plain language” refers to the preference for words that are in everyone’s vocabulary – what linguists term the “core vocabulary” – consisting of about 200 to 300 words. These words are mostly verbs, pronouns, and demonstratives, such as “his” and “that,” which help distinguish the subject the speaker or writer is referring to. These words are used frequently and across many contexts to express meaning and intent, usually without misunderstanding.
As the initiator of communication, the speaker or writer must choose words that are easily understood by the listener or reader. For example, a 10-year-old is unlikely to understand the meaning of “plethora,” so “plenty” or “a lot” would be better choices. A communicator should always consider his or her audience when communicating.