an account of the author's personal experiences
"Her new memoir is a deeply moving account of her personal experiences growing up in war-torn Syria."
an essay on a scientific or scholarly topic
"The professor submitted his memoir on quantum entanglement to the journal."
An autobiography; a book describing the personal experiences of an author.
"She published her memoir, a moving account of her childhood spent in a remote village."
In plain English: A memoir is a true story about your own life that focuses on specific events instead of every single detail from birth to now.
"She spent her evenings writing down memories for her upcoming memoir about growing up in the countryside."
Usage: Use "memoir" to refer specifically to nonfiction works focusing on particular episodes or themes from one's life, rather than a comprehensive account of every experience covered by an autobiography. Avoid using it for fictionalized biographies unless explicitly noted as such in the text.
The word memoir comes from the French mémoire, which originally meant "memory." It entered English as a distinct term for a written account of personal experiences, separate from its related forms in other languages.