From the Latin Metrum meaning a measure
"Meter" is a Greek root. It comes from the Greek word "metron," which means measure.
The Greek root word therm means heat.Common words that come from this root are "thermometer, theorem, thermal, thermos bottle, thermostat, and hypothermia." (Thanks to MSU.)
peri= around, meter= measure.
speedometer, gyronmeter, etc.
The root word for sphygmomanometer is "sphygmo," which comes from the Greek word "sphygmos," meaning pulse.
Don is not a Greek root word.
meter means measurment
life
it is not a greek root or any root
Assuming you mean cred- as in incredible, credibility, etc., it comes from the Latin word credere (to believe).
The root mem is not greek, but latin. It means 'mind'.
The Greek root carci- means cancer