Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
stock-still is an adjective and adverb meaning "absolutely still". It carries 2 recorded senses.
without moving or making a sound
“he sat still as a statue”
“time stood still”
“they waited stock-still outside the door”
“he couldn't hold still any longer”
Definitions, synonyms and semantic relations for stock-still come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.