Definition of act upon

The phrase "act upon" is a phrasal verb in the English language that carries two meanings: "to take action in response to" and "to have an effect on." The origin of the phrase can be traced back to Old English, where it was formed by combining two separate words: "actan" (meaning "to do") and "upon" (meaning "toward" or "into the presence of"). The first part of this verb, "act," has a long linguistic history. It comes from the Old English verb "aeçtan," which meant "to make" or "to create." This word was derived from the Proto-Germanic root "aktuz," which had a similar meaning. As English evolved, the word "act" took on a more specific meaning, referring to something that is performed or carried out, such as a play or a legal proceeding. In this context, "upon" (meaning "toward" or "into the presence of") was added to indicate that the action being referred to is being taken in response to something else. Over time, the meaning of "act upon" has expanded to encompass the idea of having an effect on something, as well. This more complex meaning likely arose as a result of the influence of Latin and French. Both languages had verbs that meant "to be affected by" or "to result from," such as Latin "ageri" (meaning "to be carried out") and French "avoir à" (meaning "to be obliged to"). Today, the phrasal verb "act upon" is widely used in English, particularly in the contexts of law, literature, and science, where it is often followed by a preposition, such as "upon" or "upon receipt of." The verb's dual meanings reflect the complexity and richness of the English language, demonstrating both the evolution of English over time and the ongoing interaction between English and other European languages.