Full Idea
The word 'part' can used whether it is attached, or arbitrarily demarcated, or gerrymandered, or immaterial, or unextended, or spatial, or temporal.
Gist of Idea
Parts may or may not be attached, demarcated, arbitrary, material, extended, spatial or temporal
Source
Achille Varzi (Mereology [2003], 1)
Book Reference
'Stanford Online Encyclopaedia of Philosophy', ed/tr. Stanford University [plato.stanford.edu], p.2