Risk-free is an adjective used to describe a situation, action or investment that has no chance of failure or loss. Synonyms for the term risk-free include 'guaranteed,' 'secure,' 'certain,' 'safe,' 'assured,' 'tested,' 'dependable,' 'well-established,' 'well-proven,' 'unfailing,' 'steady,' 'unwavering,' 'reliable' and 'foolproof.' These words carry similar connotations and are often used interchangeably with risk-free to convey the idea of an event, investment or outcome that is unlikely to fail or cause harm. Choosing the right synonym depends on the context and the level of certainty required. Regardless, these words convey the same sense of safety and assurance that something is free from danger or risk.