stiffened

Because it is a word with a single syllable, stiffened is not hyphenated. The words that have a single syllable are called monosyllabic words.

Using the Knuth-Liang algorithm, we calculated the hyphenation for the word you’ve entered. However, this hyphenation has not been verified against authoritative sources and may be approximate. This is because the algorithm relies on pre-defined patterns that may not cover all exceptions, contextual variations, or irregular spellings. We are working to verify hyphenations against trusted sources to ensure greater accuracy.