Informal To or in Australia or New Zealand.(adverb)
Australia and often New Zealand.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "down under" in a sentence
"Also, my mom adored him, so she would probably support the union somewhere deep down under her churchly morals."
"Sections of the text were broken down under headers such as SOIL TRANSMOGRIFICATION and BIO-AGENT “V,” with accompanying details, technical information, and scientific formulas."
"Kinseth Roberts breathed heavily for at least twenty minutes, then finally reached down under the covers to remove their shoes."