気味 is used to say that someone or something has a slight tendency or shows signs of a state, often one that is not desirable. It is similar to saying "a bit" or "-ish" in English. For example, if you are a little tired, you can say 疲れ気味. It is commonly used with health conditions (like 風邪気味, meaning "a bit like having a cold") and with trends (like 太り気味, meaning "tending to gain weight"). The nuance is that the state is not fully developed but is noticeable.

You can also use it with verbs by taking the ます-stem (the form used before ます, like 疲れ from 疲れます). So, 忘れ気味 means "rather forgetful" or "tending to forget." This pattern is useful in everyday conversation, especially when describing your own condition or making a mild complaint.