also: あたまくだし
adverb
unsparingly; without listening; without giving a chance to explain
Used adverbially, often with verbs like 叱る (scold) or 否定する (deny), to describe an action done without hearing the other person out. The more common form is 頭ごなし (あたまごなし).
See also: 頭ごなし
彼は私の言い分を聞かずに、頭ごなしに叱った。
He scolded me unsparingly without listening to what I had to say.
頭ごなしに否定するのはよくない。
It's not good to deny something without giving the other party a chance to explain.
The standard modern form; 頭くだし is a rare variant with the same meaning.
The exact derivation is uncertain; the spelling 頭ごなし suggests a combination of 頭 (head) and ごなし (from ご無し, meaning 'without'), implying 'without using one's head (to listen)'.