Collocations for theoretical - adj.

be
remain

highly
merely
purely
This research is purely theoretical.

largely

Theoretical is used with these nouns:
advance, analysis, approach, argument, aspect, basis, chemistry, coherence, concept, consideration, context, discussion, distinction, economics, exercise, explanation, foundation, framework, grounding, groundwork, idea, implication, importance, insight, issue, justification, level, limit, linguistics, model, perspective, physicist, physics, point of view, position, possibility, prediction, principle, proposition, puzzle, reflection, science, significance, sophistication, standpoint, study, training, treatment, understanding, work, writing