Here are all the possible meanings and translations of the word Pasadena. Princeton's WordNet(0.00 / 0 votes)Rate this definition: Pasadena(noun) a city in southwestern California to the east of Los Angeles. Pasadena. Pasadena is a city in Los Angeles County, California, United States. As of 2010 United States Census, the population of Pasadena was 137,122, making it the 180th-largest city in the United States, down from 168th place in 2009.