Standardized extract
A botanical extract guaranteed to contain a minimum percentage of a specific "marker" compound believed to drive the plant's effects (e.g. withanolides in ashwagandha, curcuminoids in turmeric). An unstandardized extract or raw powder carries no such guarantee -- it may contain a similar compound at a much lower, unknown concentration.
Example
Only 3.2% of on-market ashwagandha products (70 of 2,159 with a recognised form) are labelled as a standardized extract of >=5% withanolides, the material used in a widely cited 64-person trial (Chandrasekhar 2012); 49.6% are plain root powder or do not name a form (the site assigns those to root powder), neither of which guarantees withanolide content.