New (2019) definition:
Information is material if omitting, misstating or obscuring it could reasonably be expected to influence decisions that the primary users of general purpose financial statements make on the basis of those financial statements, which provide financial information about a specific reporting entity.
Omissions or misstatements of items are material if they could, individually or collectively, influence the decisions or assessments of users made on the basis of the financial statements. Materiality depends on the nature and size of the omission or misstatement judged in the surrounding circumstances. The nature or size of the item, or a combination of both, could be the determining factor.« Go to IFRS Jargon