Free

The word is “dorea”. It is given three definitions in the BDAG Greek-English Lexicon.
1. Being freely given, a gift, without payment, gratis.
It is used with this meaning in these verses:
“Heal the sick, raise the dead, cleanse the lepers, cast out demons. Freely you received, freely give. (Mat 10:8)
being justified as a gift by His grace through the redemption which is in Christ Jesus; (Rom 3:24)

2. Being without contributory fault, undeservedly, without reason or cause.
It is used with this meaning in the following verse:
“But they have done this to fulfill the word that is written in their Law, ‘THEY HATED ME WITHOUT A CAUSE.’ (Joh 15:25)

3. Without purpose, in vain, to no purpose.
The word is used with this meaning in the following verse:
“I do not nullify the grace of God, for if righteousness comes through the Law, then Christ died needlessly.” (Gal 2:21)

In all four verses it is the same word “dorea.” In each verse it is used in a different sense.

With each use we gain a fuller sense of the free gift of our justification by the grace of God through the redemption which is in Christ Jesus and given to us by our faith in Jesus Christ.