noun, noun or participle which takes 'suru', transitive verb, intransitive verb
hesitation; indecision; vacillation
Used as a noun or with する: 躊躇する means to hesitate or be unable to decide, and can be intransitive or take an object such as a plan, action, or decision one hesitates over. 躊躇なく means 'without hesitation.'
彼女は少しも躊躇せずに申し出を断った。
She turned down the offer without the slightest hesitation.
Considering the high cost, I hesitate to introduce it.
緊急の場合は、躊躇なく連絡してください。
In an emergency, please contact us without hesitation.