Freebase
All drugs that can be used intranasally, intrarectally or intravenously are in salt form, usually the hydrchloric salt (HCl). This is because those ROA's must use a drug that is water soluble. Salts are all water soluble because they are polar. If a drug was to be liberated from its salt base, it would be called a freebase, and would then be non-polar.
In DMT extractions, most of the time inside the plant matter the DMT is produced with a tannin salt (as opposed to the normal HCl in pharmaceuticals). Tannin is a weak base which can be overpowered in an Acid Base extraction by other acids such as vinegar (the most common) or hydrochloric acid/mutraic acid. Tannin can also be subject to the Straight to Base extraction involving NaOH/lye.
When the extraction has come to the freebase DMT, it can be pulled by a non-polar substance, usually Naptha.