#1479 ἐθελοθρησκία ethelothreskeia {eth-el-oth-race-ki'-ah}

 from G2309 and G2356; TDNT - 3:155,337; n f

—Greek Word Study (Transliteration-Pronunciation Etymology & Grammar)

 1) voluntary, arbitrary worship
    1a) worship which one prescribes and devises for himself,
        contrary to the contents and nature of faith which ought
        to be directed to Christ
    1b) said of the misdirected zeal and the practice of ascetics

—Thayer's (New Testament Greek-English Lexicon)

—Strong's (Greek Dictionary of the New Testament)

—NAS Exhaustive Concordance of the Bible with Hebrew-Aramaic and Greek Dictionaries

 AV - will worship 1; 1

—Exhaustive Concordance (KJV Translation Frequency & Location)