- To customize is defined as to make or change something to personal or unique specifications.
An example of customize is to have your car modified with leather seats, a top of the line sound system and glowing lights.
transitive verbcus·tom·ized, cus·tom·iz·ing, cus·tom·iz·es
(third-person singular simple present customizes, present participle customizing, simple past and past participle customized)
custom + -ize. First attested in 1934 in American English.