There are some words in English so prone to misunderstanding that they should not be used. We already know that some words, like hot, have many meanings. (High temperature, attractive, spicy, radioactive, stolen and so on...) Usually we can choose the correct meaning of hot from context, but not always.
This food is hot.
This sentence could mean the food has many chilli peppers in it and/ or it has just come off the stove. Sometimes guessing the meaning is difficult and if safety is involved we should avoid misunderstandings.
Here are the three most dangerous words:
The word inflammable is famous for being misunderstood. It means that a thing can burn, but usually the prefix in- means not. So like the word inhabitable, meaning can be lived in, confusion is easy and dangerous.
For example, a (stupid) quotation about candle safety:
"If you light a candle it should be resting on something inflammable like a saucer or candle holder."
To avoid accidents, use the words flammable and not flammable or non-flammable and never use inflammable. I know someone who bought an inflammable candle holder; it almost caused a fire in his flat.
The word flu is commonly misused to mean the mild disease also called a cold. A person with a cold will usually sneeze a lot and be ill for about 2 days. The word flu is in fact short for influenza, a serious and possibly deadly disease. A person with influenza will have a high fever and be ill for about 2 weeks. Very old, young and sick people who catch influenza sometimes die. Hundreds of thousands of people die of influenza every year. To avoid confusion, don't use the word flu. (See also flue, flew)
For example, a (stupid) quotation about the flu being harmless:
"...the swine flu is just like any other flu – mostly harmless."
The word fluorescent is used to describe brightly coloured clothing. In science the word fluorescent is used to describe material that produces visible light from the invisible light of other wavelengths such as ultraviolet light. Fluorescent material often looks brightly coloured in sunlight. So many people just assume brightly coloured is the meaning. Brightly coloured is now a common usage of the word fluorescent. The danger is that the word fluorescent is used when describing safety clothing.
For example, a (stupid) quotation about child safety:
"Dress brightly. When you go out on a dark day or nearly night, wear colourful or fluorescent clothing so the cars can see you coming."
Fluorescent clothing is often very dark at night. Do not use the word fluorescent when you mean brightly coloured or reflective. A child wearing fluorescent clothing at night is more likely, not less likely, to be hit by a car. Only use the word fluorescent in science.
There are many other less dangerous but still confusing words. These include bimonthly which can mean both twice a month and once every 2 months. The same problem exists for biannual and biweekly. If you have to play rent on your flat bimonthly, make sure which meaning is being used.
Some Hong Kong people mispronounce three as free, which is a problem when selling something for three dollars. Likewise, -ty and -teen endings may be confused; when I first came to Hong Kong, I dropped an ice-cream snack and walked out of the store, when I was told the price was HK$60 not HK$16.
Cakes are not usually made with flower. Do not use the spelling bridle when describing a woman about to get married; she might hit you. However these other confusions are not likely to kill you.
With dangerous words the second meaning may be correct or just a common error. Since life and safety can be at risk avoid using confusing words. When someone else uses them at first assume the dangerous meaning, until you can check the meaning the speaker intended.