In classical Greek αποφράζω, αποφράσσω, or αποφράττω (depending on the dialect that you spoke) meant to block something up, with medical connotations. It could refer to any type of blockage—arterial, airway, intestinal, ureteric. Hippocrates, for example, recommended blocking up an anal fistula with lint, as one form of treatment. However, in modern Greek it can also mean to unplug something or to remove a blockage, for example in a drain. So, when a cigarette advert claims that smoking “clogs” your arteries, it is suggesting that it clears them, not the other way round. The problem arises from the preposition απο-, which can either reinforce or reverse the meaning of the verb that it qualifies.3
Of my large collection of Janus words in English, only “aspirate” has any kind of medical connotation: to aspirate fluid from a cavity is to suck it out; to aspirate the letter aitch you blow out air from the mouth.
Otherwise, the closest I have come to finding a medical Janus word or term is “lupus anticoagulant,” which is actually a marker of coagulation.4
Perhaps there are more medical Janus words, but one hopes not. Ambiguity in medical discourse should be avoided whenever possible.
English Janus words
Awful—this originally meant awe-inspiring; now it means unpleasant, disagreeable, objectionable, or bad.
Bad—in modern slang means good.
Bomb—in the UK a bomb is a success (it went like a bomb) in the US it’s a flop (it was a complete bomb).
Boned—with bones (her face is well-boned) or without bones (this fish has been boned).
Chuffed— chuffed, from Middle English chuffe, a boor or a clown, means disgruntled, but if it comes from chuff or chub, meaning swollen or chubby and round-faced, and therefore happy, it means something more like gruntled, to evoke P G Wodehouse.
Cleave from the Old English cleofan means to divide (German klieben); but cleave, from the Old English clifian, means to unite (German kleben).
Clip—you can clip a note to a newspaper and clip a coupon out of a newspaper.
Draw—to draw the curtains can mean to open or close them.
Dust—to dust the furniture is to take the dust off; to dust a cake with icing sugar is to put it on.
Fast—if you move fast you move quickly; if you are stuck fast you don’t move at all.
Go—he’s a real goer, but recently he’s started to go.
A good deal—if you pay a good deal you pay a lot, if you get a good deal you pay a little.
Handicap—a handicap is a disadvantage if you have it, except at golf, where it disadvantages your opponent.
Help—I’ll help you do that, if you can’t help doing it.
In charge of—the baby-sitter was left in charge of the baby; the baby was left in [the] charge of the baby-sitter.
Left—some people left and others were left.
Let—to let (Anglo-Saxon læten) means to allow; to let (Old English letten, læt slow) means to prevent; in the latter sense a let at tennis is an obstruction by the net.
Lose no time— When someone sent Henry James an unsolicited manuscript he replied that he would lose no time in reading it; did he mean to read it immediately or not at all?
Lucky—“You’ll be lucky to get this man to work for you”; the ambiguity is clear.
Mortar is used to build a house; a mortar could be used to blow it up.
Out—if the sun is out it is visible; if the lights are out they are invisible.
Overlook—to overlook is to watch closely or to fail to see; similarly, oversight, its nounal equivalent.
Patron—a patron of the arts is someone who gives; a patron of a shop is someone who buys.
Priceless can mean both invaluable and absurd.
No question that = it is certain; no question of = it is impossible.
Off—Not on, but if the alarm clock goes off, it’s on.
Quite—someone who is quite pretty is a little attractive; someone who is quite lovely is very attractive.
Ravel—to ravel can mean to tangle and to disentangle.
Resign—If you’ve resigned you’ve given up; if you’re resigned to something, you do it.
Riverine originally meant on the bank and later came to mean in the river; opposition by association.
Roar—to laugh or to cry.
Room—a room is an enclosed space (go into the room); room is unbounded space (give me room); the living-room is an enclosed space; lebensraum is a large space.
Sanction—if you apply sanctions you prevent someone from doing something; if you sanction an action you permit it.
Scan—to scan a poem implies reading it carefully; to scan the newspaper is to read it hastily.
Screen—when cinemas screen films they show them; when nurses screen patients they hide them.
Seeded—when a field is seeded it has seeds added; when grapes are seeded they have their seeds removed.
Skin—to skin a sausage is to put on its skin; to skin a banana is to remove its skin.
Stone—when my grandmother made damson jam she didn’t bother stoning the fruits, you had to pick them out of the jam yourself when eating it; biblical stoning, on the other hand, involved the addition of stones.
Table—to table a proposal at a meeting is to put it forward for immediate discussion, but not in the USA, where it can mean to postpone discussion.
Temper—to temper your rage is to soften it; to temper steel is to harden it.
Think better—to think better of one plan than another is to prefer to do it; to think better of something is to prefer not to do it.
Through—if the telephone operator tells you you’re through, you’re ready to talk; but at the end of the conversation, you’re through.
Trim—if you trim the Xmas tree you add decorations to it; if you trim the hedge you cut it.
Trying—if you are trying hard you are doing your best; if you are very trying you are doing your worst.
Ullage—the ullage is either the amount of liquid the barrel contains or the amount by which it is short of being full (Old French œiller, to fill up); the optimist’s glass is half full, the pessimist’s half empty.
Wear—if something wears well it lasts, but cloth will eventually wear out.
Weather—we weathered the storm and came out unharmed, but the stone that’s weathered doesn’t do so well.
Wee—in Scotland, if you ask someone how long they’ve been having a particular symptom, you may get one of two answers: Oh, just a wee while (a short time); Oh, quite a wee while (a long time).
Wicked—see “bad.”
Wind up—to wind up a watch is to start it; to wind up a lecture is to end it.
With—Britain fought with France (against Germany); but Britain also fought with Germany.
Yield—to yield to an opponent is to give in; to yield a crop is to give out.
