The word "to scathe" is the synonym of the word "to harm" or "to injure". However, I have never noticed how somebody uses it. Is it OK to occasionally use it instead of "to injure" during speaking and writing?
The verb itself is almost never used in every day English, but there are two adjectives formed from it which are common:
- "scathing" means extremely harsh, biting, critical; e.g. "he launched into a scathing attack on his opponent's policies"; "the review was scathing in its criticism"
- "unscathed" means "unharmed"; e.g. "despite the dramatic accident, he escaped unscathed"
I would classify both of these as a kind of "fossil" - although clearly derived from the present and past participles of "to scathe", they are used only as distinct adjectives.
"Unscathed" has the additional distinction of being an "unpaired word" - although it should logically be the opposite of "scathed", that word is rarely used except in deliberate word play. It would be more natural to say "was almost unscathed" or "was not unscathed" than "was barely scathed" or "was scathed".
It has limited used, it isn't used as a general verb, it is mostly seen in participle form, and often in negative sentences.
So don't say "Ronaldo was scathed in the second half" or "I scathed my ankle playing tennis". You can say:
The match turned nasty in the second half, with two red cards, but Ronaldo was unscathed.
I slipped and fell, but was barely scathed.
And there is a related adjective "scathing" which means bitterly critical.
The Prime Minister led a scathing attack on the oppositions policies.
As the other answers explain, it is not usually used. However it is likely to be understood if used in humor, especially if "unscathed" is spoken by someone first.
What's funny about the scene below is that "scathed" is an unusual word, but understood to be the opposite of "unscathed" which is much more commonly used.
Sometimes it's helpful to see it used in context. In the American TV show The Sopranos a truck driver being robbed was afraid that if he looked unharmed, his boss might think he was part of the crime, and not a victim.
You can read about it in the episode summary in Wikipedia 46 Long:
Christopher and Brendan Filone, who has a meth habit, hijack a shipment of DVD players and are pleased to "scathe" the truck driver, at his request, so that he cannot be suspected.
And I've transcribed the bit of the dialoge from the video The Sopranos - "You wanna be scathed"
Driver: Look I don’t know who in the company gave up the route, but there’s no way I could walk away unscathed without being fired.
Christopher: You want to be scathed?
Driver: Yeah, so it looks like I didn’t give up without a struggle.
Driver is punched and kicked
The answers with the meaning are great, but to give specific answers: "never" and "no". Despite being in the dictionary, scathe is dead. It's not even in old movies or historical legal documents. It's so dead that it's considered a made-up word playing off of scathing or unscathed. Using it as a serious synonym for injure would be confusing.
Because of unscathed, scathe is vaguely associated with injury. In "I scathed my hand", scathed jumps out -- "you did what? What's a scathe? No wait, I just had lunch. Don't tell me". In a fantasy book we might assume a scathed hand is a magical injury to be explained later.
Also because of unscathed, scathed is a joke word. If you said "2 people were scathed in a car crash", you're making light of their injuries. A listener's thought process might be: "scathed isn't a word -- it's a play on either scathing or unscathed. The opposite of completely unhurt could be killed, or it could be very minor injuries. Or maybe they heard the driver was unscathed and are stupid and think scathed is a word. Or they might have mispronounced unscathed?"
The common phrase scathing insult gives another possible guess. "John is going to scathe you" sounds like made-up teen-age dialogue. He's going to humiliate you, but nothing physical. In fact, Merriam Webster's current online example of recent use has "Monday Night Football debates always seem to scathe a few players". It means mock or insult, as a play on scathing comments.