ma·nip·u·lan·dum \məˌnipyəˈlandəm\noun (pluralmanipulan·da \-də\) Etymology: New Latin, from English manipulate + Latin -andum (neuter of -andus, 1st conjunction gerundive ending) psychology: something that is or is to be manipulated < the instigator and manipulandum of behavior, the matrix within which all action must be described — R.R.Sears >