The definition of an epistle is an especially long and formal letter, or is a poem or other writing in letter form.
(noun)A very long and formal letter is an example of an epistle.
See epistle in Webster's New World College Dictionary
noun
Origin: ME epistel < OFr epistle (& OE epistol) < L epistola, epistula < Gr epistolē, a letter, message < epistellein, to send to < epi-, to + stellein, to send, summon: see stalk
See epistle in American Heritage Dictionary 4
noun
Origin:
Origin: Middle English epistel
Origin: , from Old French epistle
Origin: , from Latin epistola
Origin: , from Greek epistolē
Origin: , from epistellein, to send a message to
Origin: : epi-, epi-
Origin: + stellein, to send; see stel- in Indo-European roots
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