1) Not having rotation 
• (a.) Not rotatory; passing from one point to another by a movement other than rotation; -- said of the movement of parts of a liquid or yielding mass.
Ir`ro·ta'tion·al adjective (Physics) Not rotatory; passing from one point to another by a movement other than rotation; -- said of the movement of parts of a liquid or yielding mass. Sir W. Thomson. 
not having rotation. · conservative (def. 7).