Underpin v. t. : To lay stones, masonry, etc., under, as the sills of a building, on which it is to rest.

Underpin v. t. : To support by some solid foundation; to place something underneath for support.

Example:
Removing Underpin on a mobile home?

Taxonomy
Merriam-Webster Online Dictionary, Dictionary, webster, pin, Word Games, Webster Online Dictionary with audio pronunciations, thesaurus, Google Search, Custom Search, glossary, english, language, ESL, Search, transitive verb, thesis, evidence, foundation.

Defination from the web:
underpin from the Merriam-Webster Online Dictionary with audio pronunciations, thesaurus, Word of the Day, and word games. ... substantiate <underpin a thesis with evidence> 2 : to form part of, strengthen, or replace the foundation of <underpin a structure> <underpin a ...