We teach you how to use them in different situations . And sometimes we explain where these terms come from . Today , we talk about feeling sick . We have all felt sick at some point in our lives . And our condition can go from one extreme to the other . If I am very sick , you could say I am as sick as a dog . Other times I may feel good enough to go to work , but still not great . When I feel tired , worn out or just a little sick , I can say I am feeling under the weather . This is probably the simplest , most common way to say , “I don't feel well .” In fact , I could not think of another phrase that expresses the same meaning as well as “under the weather ” does . When you are under the weather , your condition is not serious . You do not need to be in a hospital or see a doctor . You have too much alcohol to drink one night and the next day , you feel sick . However , I have never heard the idiom used this way . When I hear someone say they are under the weather , I imagine they are not feeling well , but nothing else . On this program , I hardly ever use the word “always ,” but it is always acceptable to use this expression when speaking with others . Feel free to tell your co-workers , your best friend or even your 90-year-old grandmother that you are “under the weather .” We will give more examples after we learn where this expression comes from . So don't go away ! Now , bad weather can affect your health . For example , if I'm caught in a cold rainstorm for several hours without proper protection , I very possibly will get sick . But why do we say under the weather when we're sick ? That just sounds strange . To find out , I turned to a publication called Farmers ’ Almanac . Farmers ’ Almanac is not really meant for language learners . It was founded in 1818 to help American farmers understand more about the natural world around them as they grow and harvest their crops . That is still its purpose today . So , if an idiom is weather-related , it probably will be explained in the Farmer's Almanac ! To explain , “under the weather ,” the website published the writing of Richard Lederer , a word expert . Lederer notes that the expression “under the weather ” comes from the language of sailors . Imagine being on a boat on rough seas . The waves continually force the boat up and down and side to side . This continual movement can make many people feel seasick . They actually went “under the weather ” to find safety , shelter and to avoid becoming seasick . Years ago , only sailors described seasick sailors as being “under the weather .” But today , we use this expression anytime someone is not feeling well . Now , let me use this phrase in a few sentences . I just can't go out tonight . I am feeling under the weather . But thanks for the invite . After standing outside in the cold rain waiting to buy concert tickets , the young woman awoke the next day feeling under the weather . If you feel under the weather , you should really go home and rest . Join us again next time when we explore another word or expression in American English .