Etymology: Middle English, from Old English swā; akin to Old High German sō so, Latin sic so, thus, si if, Greek hōs so, thus, Latin suus one's own — more at suicide
Date: before 12th century
a. in a manner or way indicated or suggested <do you really think so> — often used as a substitute for a preceding clause <are you ready? I think so> <I didn't like it and I told her so> b. in the same manner or way ; also <worked hard and so did she> c. thus 1 <for so the Lord said — Isaiah 18:4 (Authorized Version)> d. then, subsequently <and so home and to bed> 2. a. to an indicated or suggested extent or degree <had never been so happy> b. to a great extent or degree ; very, extremely <loves her so> c. to a definite but unspecified extent or degree <can only do so much in a day> d. most certainly ; indeed <you did so do it> e. most decidedly ; surely <I so don't believe you> 3. therefore, consequently <the witness is biased and so unreliable> Usage: The intensive use of so (sense 2b) is widely condemned in college handbooks but is nonetheless standard <why is American television so shallow? — Anthony Lewis> <the cephalopod eye is an example of a remarkable evolutionary parallel because it is so like the eye of a vertebrate — Sarah F. Robbins> <the kind of sterile over-ingenuity which afflicts so many academic efforts — Times Literary Supplement>. There is no stigma attached to its use in negative contexts and when qualified by a dependent clause <not so long ago> <was so good in mathematics that he began to consider engineering — Current Biography>. The denotation in these uses is, of course, slightly different (see sense 2a). Another emphatic use of so (sense 2e) has developed more recently and occurs mostly in informal contexts. II. conjunction Date: before 12th century 1. a. with the result that <the acoustics are good, so every note is clear> b. in order that <be quiet so he can sleep> 2. archaic provided that 3. a. for that reason ; therefore <don't want to go, so I won't> b. (1) — used as an introductory particle <so here we are> often to belittle a point under discussion <so what?> (2) — used interjectionally to indicate awareness of a discovery <so, that's who did it> or surprised dissent Usage: Although occasionally condemned, use of so to introduce clauses of result (sense 1a) and purpose (sense 1b) is standard. In sense 1b so that is more common in formal contexts than so alone. III. adjective Date: before 12th century 1. conforming with actual facts ; true <said things that were not so> 2. marked by a desired order <his books are always just so> 3. — used to replace a preceding adjective <was witty by adult standards and of course doubly so by mine — Sally Kempton> IV. pronoun Date: before 12th century 1. such as has been specified or suggested ; the same <if you have to file a claim, do so as soon as possible> 2. — used in the phrase or so to indicate an estimate, approximation, or conjecture <stayed a week or so> <cost $15 or so> V. variant of sol VI. abbreviation south; southern
New Collegiate Dictionary. 2001.