The phrase "doest top your head" may seem archaic, but it has a specific spelling and pronunciation. In IPA phonetic transcription, it is written as /ˈdʌst tɒp jɔːr hɛd/. The "doest" part comes from the old English word "doeth," meaning "does." The "top" part is straightforward, but "your" is spelled as "yore" in this case due to historical differences in English spelling. Overall, "doest top your head" should be pronounced as "duhst top yore hed."
"Off the top of your head" is an idiomatic expression that refers to providing an immediate or spontaneous response or answer without taking time to think about it or consult any references. The phrase suggests that the information or response is being given from one's memory or knowledge without any prior preparation or research.
When someone is asked a question or tasked to recall a particular detail, they may respond with the phrase "off the top of my head" to indicate that they are giving an answer based solely on what they can immediately recollect without any extensive thought or research. It implies that the information provided may not be exhaustive, completely accurate, or precise.
The phrase also implies that the person offering the response may not be confident in its accuracy or may be unsure if they have remembered everything correctly. It is often used as a way to signal that the information shared should be verified or treated as approximate rather than being unquestionably correct.
Overall, "off the top of your head" conveys the idea of providing a rapid response or answer based on personal knowledge or memory without relying on external sources or corroborating evidence.