Genetic factors may influence how the central nervous system reacts to nicotine. 4. Something that causes another thing to happen
cause noun [countable]:
Scientists are still trying to find the cause of the disease.
Investigators have visited the scene to establish the cause of the accident. (=find out what the cause is)
Polluted water is one of the major causes of death among young children in some countries.
Almost certainly, the underlying cause of the war was the need for oil. (=the most important cause, even though it is not immediately obvious)
Scarman was in no doubt that the root cause of the rioting was unemployment and poor living conditions. (=the most important cause, even though it is not immediately obvious)
factor noun [countable] one of several causes of a situation or condition:
The research tried to identify the key factors (=most important factors) affecting economic change.
The committee studied a wide range of social, economic, and environmental factors.
Studies have shown that alcohol is a contributory factor in 10% of all accidents in Britain (=it is one of the things that causes accidents, often in combination with other things)
Cost is often the deciding factor when choosing any product. (=the main factor that makes you choose to do something) origins noun [plural] the first causes from which a situation, condition etc has developed:
The book describes the origins of modern science.
The origins of Sudan's debt crisis go back to the early 1970s.
For some patients, understanding the origins of their fears is a long and painful process.
The dispute between the two families had its origins in the battle of Wakefield.
source noun [countable] something that causes something else to develop, for example a disagreement, a feeling, or an infection:
Housework can become a major source of conflict between couples.
The fact that the two words are so similar can be a source of confusion.
Further study was necessary to identify the source of the infection.
root noun [countable] the original and most important cause of something, especially a problem:
They failed to get to the root of the problem. (=discover the main cause)
Bad experiences in childhood lie at the root of many psychological disorders. (=they are the main cause)
Certainty & Uncertainty
1. Ways of saying that you are certain about something 2 Ways of saying that you are not certain about something
1. Ways of saying that you are certain about something
certain adjective if you are certain about something, you are absolutely sure that it is true. If a fact is certain, it is definitely true, or it will definitely happen:
I am certain that his analysis is correct.
It now seems certain that the earth's climate is starting to change.
One can never be absolutely certain of anything in science.
The general addressed the troops before the battle, assuring them that victory was certain.
STUDY NOTE: Grammar
Certain is more formal than sure. It also sounds more definite.
sure adjective [not before noun] if you are sure about something, you believe that it is definitely true or correct:
I am sure that many other writers share this view.
It is difficult to be absolutely sure about when the photograph was taken.
convinced adjective [not before noun] completely sure that something is true, especially when you cannot prove it but you have strong feelings about it:
She was convinced that her husband was innocent.
They became convinced of the need for better health education.
confident adjective [not before noun] sure that something good will happen, or that you will be able to achieve what you want:
The researchers were confident of success. (=they were sure that they would succeed)
In his report he said he was confident that standards would improve.
satisfied adjective [not before noun] sure that something is true, because you have enough information to make a decision:
Professor Knowles is now fully satisfied that (=completely satisfied) the drug is safe for general use.
The insurance company needed to be satisfied that the damage was caused by the storm.
have no doubt / be in no doubt to be so certain about something that there are no doubts in your mind:
I have no doubt that a cure for the disease will one day be found.
He said that he was in no doubt that the fire was started deliberately.
without (a) doubt used when you are completely sure about something:
She was without doubt one of Mexico's finest artists.
His experience in London was, without doubt, very important to his career as a writer.
Without a doubt, it is what we eat that determines our weight.
there is no doubt that (also there is no denying / disputing the fact that) used when you are completely sure about something:
There is no doubt that violence on our TV screens does influence children.
There is no denying the fact that these men are guilty of the most horrendous crimes.
There is no disputing the fact that new technology has had a dramatic effect on our lives.
certainly / undoubtedly adverb used when you want to emphasize that you are certain of what you are saying:
Businesses will certainly benefit from the new tax laws.
Undoubtedly there is a link between smoking and lung cancer.
Certainly it will be a long time before humans are able to live in other parts of the solar system.
Beckham was the captain and undoubtedly the best known player in the England team.
2. Ways of saying that you are not certain about something
not certain / uncertain adjective [not before noun] not sure about something:
I am not certain that the figures are accurate.
People often feel uncertain about how to deal with this type of situation.
It is uncertain whether his death was accidental.
It is by no means certain that she is right. (=it is not at all certain)
STUDY NOTE: Grammar
Not certain/uncertain is more formal than not sure.
not sure / unsure adjective [not before noun] if you are not sure about something, you do not know exactly what it is, whether it is true, what to do etc:
I am not sure whether this story is true or not.