確か【たしか】
sure, certain, positive, definite, reliable, trustworthy, safe, sound, firm, accurate, correct, exact, If I'm not mistaken, If I remember correctly, If I remember rightly
確実【かくじつ】
certain, sure, definite, reliable, sound, solid, safe, secure
確保【かくほ】
securing, obtaining, ensuring, guarantee, maintaining, belay, belaying
明確【めいかく】
clear, precise, definite, distinct
確認【かくにん】
confirmation, verification, validation, review, check, affirmation, identification
確立【かくりつ】
establishment, settlement
確定【かくてい】
decision, settlement, confirmation, establishment
的確【てきかく】
accurate, precise, exact, appropriate, apt, right
確率【かくりつ】
probability, likelihood, chances
確信【かくしん】
conviction, belief, confidence
確かめる【たしかめる】
to ascertain, to check, to make sure
正確【せいかく】
accurate, correct, precise, exact
不確か【ふたしか】
unreliable, uncertain, indefinite, unclear