WordNet (r) 3.0 (2006):
pigeonholing n 1: a system for classifying things into groups [syn: grouping, pigeonholing]Moby Thesaurus II by Grady Ward, 1.0:
21 Moby Thesaurus words for "pigeonholing": analysis, arrangement, cataloging, categorization, classification, codification, division, filing, grading, grouping, indexing, placement, ranging, ranking, rating, sorting, stratification, subdivision, tabulation, taxonomy, typology