Everything in language is subject to change – its sounds, spellings, meanings, and usage. Some people resist such change, wishing that words would stay still. Because of the etymological fallacy, they may even reject standard usages that became established long ago, such as alternative, decimate, and dilemma.
Luckily, etymology is not the boss of meaning – we are. And there are many right ways of using most words. This makes things more complicated but also more interesting. Pedants may claim that language use is simple, or should be – but it’s simple only if you ignore many historical, cultural, social, and other factors.
Take that word simple. Its meaning may seem simple, but that belies its range of senses and complex history. I was struck by that history, and its effect on semantics, when I read Beryl Bainbridge’s historical novel According to Queeney, which features Samuel Johnson. Peter Garrick, brother of the playwright David, was hosting some friends in 1774:
There was an atmosphere of accord in the house, which Mrs Thrale found relaxing. She was fond of her host, who had many times sat at her table in Southwark. He was not, it was true, as diverting as his brother, but that was all to the good; Davy could often be tiring, particularly after triumphing in some production at Drury Lane. The second Mrs Garrick was also likeable, being somewhat simple in the correct sense of the word.
What exactly did the narrator mean by simple? Then, as now, the word was polysemous – it had more than one meaning. The phrase ‘in the correct sense of the word’ indicates that some senses were more accepted or ‘proper’ than others – even if this says more about sociolinguistic attitudes than good or bad usage. (The use of nice in Northanger Abbey by Jane Austen presents a similar case.)
The OED entry for simple is vast, showing the many senses it has had since it entered English from Old French in the 13th century; the Online Etymology Dictionary has a summary. Over the centuries, simple has meant ‘humble and unpretentious’, ‘unsophisticated’, ‘undistinguished in office or rank’, ‘small and insignificant’, ‘bare’, ‘wretched and pitiful’, ‘lacking knowledge or learning’, ‘foolish or stupid’, ‘not complex in structure’, ‘easily done or understood’, and so on. Some of these senses shade into one another, so it’s not always obvious which one is intended.
The first sense given in the OED is ‘free from duplicity, dissimulation, or guile; innocent and harmless; undesigning, honest, open, straightforward.’ Simple has meant this for 800 years, and it still does: it corresponds to sense 5 in Macmillan Dictionary: ‘honest and ordinary’. This may be the meaning intended in Bainbridge’s book, but other interpretations are also possible – ‘unsophisticated’ or ‘lacking learning’ could be meant kindly. When a word has so many similar meanings, deducing the right one is not always simple.

Hi, Thanks for sharing useful information. My native language is not English. Your blog post is really helpful.
You’re welcome, Shaheer. I’m glad you found it helpful.