考验 (kǎo yàn) means 'to test' but specifically refers to testing someone's character, patience, or abilities under challenging conditions — a trial or ordeal. It is stronger and more serious than 试 (shì, 'to try/test') and 测试 (cè shì, 'to test machinery/skills'), which are more neutral or technical. Use 考验 when the test is difficult and reveals true qualities (e.g., patience, friendship).