"Sin of Omission" . . . it's an accomplishment and very effective as any liar or politician can tell you.
Yes, actions speak louder than words
When you sleep in a horizontal position.
Most of us lie every night :)
Yes, with body language and facial ex
If we could call ''not saying the truth is lying''
which is possible
Your question was 'without saying a word' - a gesture isn't speech and nor is writing, come to think of it. If you exclude all forms of words and anything that implies words then I'll say no, it isn't possible to lie.