The Collaborative International Dictionary of English v.0.48:

Preengagement \Pre`["e]n*gage"ment\, n.
   Prior engagement, obligation, or attachment, as by contract,
   promise, or affection.
   [1913 Webster]

         My pre["e]ngagements to other themes were not unknown
         to those for whom I was to write.        --Boyle.
   [1913 Webster]