thereby

The word “thereby” means by that means; as a result of that. In plain terms, a formal way of saying "in that way" or "as a result".

“Thereby” is pronounced theh-uh-BEYE (/ðɛɹˈbaɪ/ in IPA).

Here is “thereby” used in a sentence: “He skipped the meeting, thereby missing the announcement.”

“Thereby” is an adverb.

The word “thereby” comes from Old English. From Old English thaerbig, formed from there plus by.

“Thereby” is a fairly common word in modern English, usually learned at around the C1 level.

Thereby means "by that means" — it points to the action that produces a result, as in "the firm cut waste, thereby saving money." Therefore means "for that reason" and introduces a conclusion, as in "costs fell; therefore profits rose." Use thereby for how something happened and therefore for why a conclusion follows.

Yes, thereby belongs to formal written English and is frequent in legal, academic, and business documents. In everyday speech, people usually say "and so," "as a result," or "by doing that" instead.

Thereby is typically followed by an -ing participle that names the result of the action just mentioned: "the dam slowed the river, thereby reducing flooding." This "thereby + -ing" pattern is by far the most common way the word is used.

Thereby specifically means "by that means; as a result of that," so it always ties a result to the action just mentioned. Thus is broader: it can mean "in this way," but also "therefore," introducing a conclusion. Where both fit, thus sounds slightly less legalistic than thereby.