in the fun world of
European Union research, STREP stands for Specific Targeted Research Project. It is a research projects with participants from multiple countries (not necessarily all of them
EU), aiming at "European competitiveness" or "meeting the needs of society or community policies". This is of course very vague.
In practice, a STREP brings together some (usually 4 to 6) universities, research centers and industries, with a tangible aim. This aim is attained through a sequence of deliverables (in the order of ten), over the course of three years.
See also: European research