the.com/tachycardia

means An abnormally fast heart rate, typically over 100 beats per minute in adults at rest.

from Built from Greek parts: 'tachys' meaning swift (the same root hiding in 'tachometer') plus 'kardia' meaning heart — the same 'kardia' that gives us 'cardiac' and 'cardiology'. Greek medical writers were already combining anatomy with vivid descriptors like 'fast' or 'slow,' and 19th-century medicine formalized the pattern, pairing 'tachy-' and its opposite 'brady-' (slow) with body parts to name exactly what was misbehaving and how quickly.