These words (aver, avow) are often found in crossword puzzles. A typical clue would be "say with certainty". Exactly what is the difference in meaning between these words? they seem to be almost, but not quite, synonymous.
"Aver" means "to state with confidence" because you're certain that you're right. "Avow" means "to admit or confess" something that people may not know about you. They're quite different.