A few months ago we received an email from a suffering reader. His eyes are hurting and his ears are subject to a terrible sound. That sound is the verb lessen. Whatever happened to decrease? our discomfited reader would like to know. And couldn’t we simply ban lessen?

As plenty of other readers remind us, there are more urgent problems in the world. But a complaint like this pushes my curiosity button. Contrary to our writer’s impression, the usage of lessen rather than decrease (and rather than the other word frequently compared with these two, reduce) has, well, decreased over the last 150 years. Decrease comes from Old French, with the Oxford English Dictionary citing its first use in English as 1393. Lessen comes from adding -en to the adjective less (Old English or Old Frisian, per OED), but its use as a verb dates back to the same period, as does the use of reduce. So you can’t accuse any of these words of barging in — and why would you, anyway?

Far more interesting, to me, are the differences in usage. Do we need whatever nuance lessen supplies, or could we get by without it? English, of course, has an unusually large number of synonyms because of its polyglot roots. One way of looking at the difference between two words is by way of the synonyms we find in a thesaurus. In the online version, decrease gets 57 synonyms, lessen 47; of the most relevant synonyms, decrease shows 26 and lessen 17. But more revealing than the numbers is that these terms, synonyms for each other, possess only eight highly relevant synonyms in common. Among the synonyms unique to decrease are curb, depreciate, lower, slash, and wane. Among those unique to lessen are dilute, erode, mitigate, and taper off. Among the less relevant synonyms, decrease gets wear down; lessen gets wind down. Intelligent minds can disagree about which synonyms belong where; it is odd to find reduce defined as make less; decrease and yet not find decrease among its synonyms. But the distinctions between decrease and lessen seem right to me. I might want to say, for instance, “The size of the lake lessened [rather than decreased] the effect of the pollutants”; I would certainly want to say “The shop decreased [rather than lessened] its prices to draw customers.”

Our suffering reader points out that decrease has a logical antonym, increase. If the opposite of less is more, shouldn’t the antonym for lessen be moren? And doesn’t that sound ridiculous? Well, yes. But we have plenty of similar examples. The verb decline, for instance, is one of the synonyms for decrease, but I would use incline as its antonym only if I were talking about a patio lounger.

What’s fair to say, I think, is that with the wealth of vocabulary at our disposal in English, we enjoy richer meanings the more we pay attention to the fine distinctions among them. A synonym conveys approximately, not exactly, the same sense. Writing “We suggest she decrease the size of her bottom margin” conveys a precise meaning that could be obscured by “We suggest she lessen the size of her bottom margin.” And there’s an expressiveness in “No amount of grief counseling could lessen his loss” that we lose in the harsher-sounding “No amount of grief counseling could decrease his loss.”

And so, dear reader, in my role as the arbiter of what can and cannot be allowed into the English language, I hereby deny your request to banish lessen from the lexicon. If we truly don’t need the word, I expect it will die out on its own. And since there’s been no significant lessening of interest in the use of decrease, I doubt we’ll see any decrease there either. May a garden of meanings bloom, each in its own discrete and eloquent way.