The ordinal form of the number forty-one, describing a person or thing in position number 41 of a sequence.(noun)
One of forty-one equal parts of a whole.(noun)
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Use "forty-first" in a sentence
"I am a slow learner, in many respects, and this may be why it took me so long to begin to know how to garden: truth is, it wasn't until my forty-first year that I learned how to make a dent in the earth."
"Waterford 3, in Killona, La. in St. Charles parish near New Orleans, ranked forty-first, with a 1 in 50,000 chance each year."
"She celebrated the first Earth Day in the suburbs of Dayton, Ohio, and will observe the forty-first Earth Day at her home in Santa Fe, New Mexico."