half a century en · NOUN
Meanings
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(alt-of, alternative, singular, uncountable) Alternative form of half-century.
alt of half-century
The centre-vestibule "open" type of coach, which met with a very lukewarm reception when first introduced over half-a-century ago, is now used in increasing numbers as a non-dining vehicle.
1957 July 14, D. S. M. Barrie, “Sixty Years of British Express Trains”, in Railway Magazine, page 457: