Definition

Unstructured data is information, in many different forms, that doesn't follow conventional data models, making it difficult to store and manage in a mainstream relational database.

Comments

Data that are not in fixed locations. The term refers to free-form text in business documents and reports, news articles and social media. For example, unstructured data are found in word processing files, PDF files, email messages, Internet forums, blogs, Web pages, Twitter feeds and Facebook pages. It is estimated that 80% of all electronic data are unstructured in contrast to highly organized tables in databases.

Source

PC Magazine

NESDIS Data Management Lexicon and Related Terms 

Category

4. Data Stewardship words