plain
UK[pleɪn]US[pleɪn]
adj
Simple and without decoration; not elaborate or luxurious
adj
Easy to see, hear, or understand; clear
adj
(of a person) not beautiful or attractive
n
A large area of flat land with few trees
Etymology
The word 'plain' entered English from Old French 'plain', which itself came from Latin 'planus', meaning 'flat, level, clear'. The Latin term is thought to derive from the Proto-Indo-European root pele-, meaning 'flat, to spread', a root also connected to words like 'floor' and 'field'. The semantic journey from the physical concept of 'flat land' to the abstract senses of 'clear' and 'unadorned' is a classic example of metaphorical extension, where a simple, unobstructed physical surface becomes associated with clarity and simplicity in appearance or understanding.
Analysis
The word 'plain' is a simplex word derived from a single Latin root. It does not contain separable, meaningful morphemes in its modern English spelling.
Examples
She wore a plain black dress to the meeting.
The instructions were written in plain English.
The river winds across the vast plain.