sure

adjective:confident in one's own abilities or knowledge; certain that something is true or will happen
- She was sure she had left her keys on the kitchen counter.
adjective:free from doubt or uncertainty; reliable
- He's a sure friend who will always keep his promises.
adjective:safe; not likely to cause trouble or danger
- The bridge was built with sure foundations to withstand earthquakes.
adverb:certainly; without doubt
- Sure, I'll meet you at the cafe at three o'clock.