Thesaurus.com
Dictionary.com
Definitions

bigness

[big-nis] / ˈbɪg nɪs /
NOUN
largeness
Synonyms
STRONGEST
immensity
STRONG
amplitude enormity enormousness greatness heftiness immenseness magnitude massiveness size
WEAK
hugeness sizableness
Antonyms
STRONG
insignificance littleness smallness tininess unimportance

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.