For the meaning of "sum of parts" in Wiktionary's jargon, see Wiktionary:Criteria for inclusion#Idiomaticity.

English

Noun

sum of parts ‎(plural sums of parts)

1. Alternative form of sum of its parts

   The whole is greater than the sum of parts.

2. Used other than as an idiom: see sum,‎ of,‎ parts.

   The expression "brown leaf" is a sum of parts, since it has no idiomatic meaning: no meaning beyond "brown" + "leaf".