Webster’s Revised Unabridged Dictionary · 1913
Apple pie
Ap′ple pie′ (pī′). A pie made of apples (usually sliced or stewed) with spice and sugar.
Apple-pie bed, a bed in which, as a joke, the sheets are so doubled (like the cover of an apple turnover) as to prevent any one from getting at his length between them. Halliwell Conybeare. — Apple-pie order, perfect order or arrangement. [Colloq.] Halliwell.