Greek: δωρεαν [dôrean] (Accusative case of δωρεα [dôrea], is used adverbially). Freely, gratuitously. Without just cause, unnecessarily.

δωρεαν [dôrean] appears 9 times in the NT:

(1, 2) Matthew 10: 8
Heal the sick, cleanse the lepers, raise the dead, cast out devils: freely ye have received, freely give.

(3) John 15: 25
But [this cometh to pass], that the word might be fulfilled that is written in their law, They hated me without a cause.

(4) Romans 3: 24
Being justified freely by his grace through the redemption that is in Christ Jesus:

(5) 2 Corinthians 11: 7
Have I committed an offence in abasing myself that ye might be exalted, because I have preached to you the gospel of God freely?

(6) Galatians 2: 21
I do not frustrate the grace of God: for if righteousness [come] by the law, then Christ is dead in vain.

(7) 2 Thessalonians 3: 8
Neither did we eat any man's bread for nought; but wrought with labour and travail night and day, that we might not be chargeable to any of you:

(8) Revelation 21: 6
And he said unto me, It is done. I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely.

(9) Revelation 22: 17
And the Spirit and the bride say, Come. And let him that heareth say, Come. And let him that is athirst come. And whosoever will, let him take the water of life freely.