Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
* tertĭātĭo, ōnis, f. [tertiatus], a doing a thing the third time; concr., that which is produced by a third operation: miscere tertiationem cum primā pressurā, the oil produced by the third pressure, Col. 12, 52, 11.