SO has 2 meanings
My SO and I are both planning to go to the play with you guys.
|Cuffing||Linking up in a relationship with a person|
|Throuple||A romantic relationship between three people|
|Deal breaker||An issue that breaks up a relationship|
|DTR||Define the relationship|
|Relationship goals||An admirable relationship|
An abbreviation used in baseball statistics to count the number of strikeouts by a pitcher or batter.
The SO abbreviation is commonly used to measure a pitcher's efficiency along with his ERA, W, L, and CG. It also appears in a batter's statistics to measure how well he is hitting. The SO abbreviation can be used interchangeably with K to keep track of strikeouts.
He threw a CG with 11 SO for the W.
|ERA||Earned run average|
|RBI||Runs batted in|
Those lucky enough to be in a romantic relationship use the acronym SO to refer to their "significant other." A person's significant other is their romantic partner. Notably, the term SO is gender-neutral, so it can be used to refer to a person's bf, gf, husband, wife, or other type of partner.
As you might expect, you're most likely to encounter the SO acronym when talking with someone who is part of a couple. Some couples refer to each other as SOs simply because they prefer the term to its alternatives, while others do so to avoid "defining" their relationship too early.