All fail-safe synonyms

adj fail-safe

• sound — The, a strait between SW Sweden and Zealand, connecting the Kattegat and the Baltic. 87 miles (140 km) long; 3–30 miles (5–48 km) wide.
• confident — If you are confident about something, you are certain that it will happen in the way you want it to.
• foolproof — involving no risk or harm, even when tampered with.
• protected — to defend or guard from attack, invasion, loss, annoyance, insult, etc.; cover or shield from injury or danger.
• reliable — that may be relied on or trusted; dependable in achievement, accuracy, honesty, etc.: reliable information.
• secure — free from or not exposed to danger or harm; safe.
• sure — free from doubt as to the reliability, character, action, etc., of something: to be sure of one's data.
• reliant — having or showing dependence: reliant on money from home.