Therefore (adverb)

1. As a result; consequently.
2. For that or this reason; on that account.
3. Expressing a logical consequence; (used to introduce a logical conclusion).

Origin:

Middle english: from old english thærfore, from thær "there" + fore "before". .

Examples:

1. I am tired, therefore I will go to bed early.
2. The experiment failed, therefore we will have to try again.
3. It is raining, therefore we will stay indoors.
4. The company is not doing well, therefore we will have to lay off some employees.
5. I have a lot of work, therefore I will have to stay late.