1. (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"
2. as a consequence;
"he had good reason to be grateful for the opportunities which they had made available to him and which consequently led to the good position he now held"