So

So is a common English word with multiple grammatical functions. It functions as a conjunction, an adverb, and an interjection, and it also appears in musical notation as the solfege syllable for the fifth scale degree in many systems. Its versatility makes it a frequent discursive and syntactic tool in everyday language.

Etymology and cognates

The word originates from Old English swa or swā, meaning “in that manner, thus, to such a degree.” It is related to cognates in other Germanic languages, such as Old Norse svá and German so, and has evolved into the modern English so used today. The form remains closely linked to its sense of manner, degree, and consequence.

Usage

As a conjunction, so introduces results or conclusions: “It was raining, so we stayed indoors.” It also appears in constructions like so…that to express a high degree: “She was so tired that she couldn’t continue.” As an adverb of degree, so modifies adjectives and other adverbs: “The soup is so hot.” It can function as an interjection or discourse marker at the start of a sentence: “So, what happened next?” In certain set phrases, such as so far or so long, it participates in common idiomatic expressions.

In music, so (often written as sol or so) denotes the fifth note of the major scale in solfege, used in movable-Do and fixed-Do systems to indicate pitch.

See also

Thus, hence, such, thusness.