IPA: //ˌʌltrəˈræpɪd//
KK: /ˈʌltrəˌræpɪd/
Very fast or quick, often referring to something that happens in an extremely short amount of time.
The ultrarapid response of the system allowed it to react to changes almost instantly.
Ultrarapid is formed from "ultra-" (meaning beyond or extreme) and "rapid" (from Latin "rapidus", meaning swift or fast). The word describes something that is extremely fast or beyond the usual speed.
Think of 'ultra-' meaning beyond and 'rapid' meaning fast — together they describe something that is extremely fast.
No commonly confused words.