Literally: Sidq is truth. Veracity. Reality. Correctness. Inward honesty. The truthfulness of heart.
Conformity to haqiqah. One of the particular attributes of the Prophets.
Siddîqîn: The plural of siddîq. Those awliyâ who ever bear witness to Allah's truth. Those who are the foremost on the way of Allah through loyalty. Those who are like Hazrat Abu Bakr Siddîq (ra) and follow his way of loyalty.