This is the 9318th most frequent Russian word.
су
"Су" is not a standalone word in Russian; it is likely a shortened slang or part of a longer word. Context is needed for an accurate definition.
Here, 'су' is used as a colloquial abbreviation for 'сударь' or 'сударыня' which can be considered as a regional or stylistic context.
В су положили свежие цветы.
Fresh flowers were placed in the vase.
'су' can relate to archaic or thematic usage within formal or religious lexicon.
Слово 'су' из церковной тематики услышали прихожане.
The parishioners heard the word 'су' from the church context.
This usage of 'су' could function as an abbreviation or intentional truncation within modern colloquial speech to indicate an object.