1. finds out for certain; makes sure of
Usage: third person singular present tense of ‘ascertain’

Examples

• The detective ascertains the facts before making an arrest.
• She ascertains the meeting time by checking her calendar.
• The doctor ascertains the patient’s condition through tests.
• He ascertains the truth by interviewing witnesses.
• The researcher ascertains the data’s accuracy before publishing.
• The inspector ascertains that all safety measures are in place.