(used to introduce a logical conclusion) from that fact or reason or as a result
"therefore X must be true"
"the eggs were fresh and hence satisfactory"
"we were young and thence optimistic"
"it is late and thus we must go"
"the witness is biased and so cannot be trusted"
From there, from that place or from that time.
"After leaving the station, he waited thence for his friend to arrive before they continued their journey."
Thence comes from Middle English, where it originally combined a word meaning "from there" with an adverbial ending. Its roots trace back to the Proto-West Germanic language family.