This word comes directly from the Greek blasphemeo, which is believed to derive from blapto (to injure) and pheme (speech), hence injurious speech.
Scripture speaks of those who blaspheme God (Rom. 2:24; 1 Tim. 6:1). It is also possible to blaspheme Christ, as certain hateful ones did at the cross when they "reviled" or "railed on" (blasphemeo) the Lord (Mt. 27:39; Lk. 22:65).
We must also be cautious that we do not conduct ourselves in such a way as to cause the "word of God" to be blasphemed (Tit. 2:5; cf. 1 Tim. 6:1). This can happen by teaching falsely or by living a corrupt lifestyle while professing loyalty to God. Such may cause sacred things to be spoken against.
The controversial passage about "blasphemy against the Spirit" (Mt. 12:31) has troubled many because, in some sense, it suggests that this transgression is beyond forgiveness. However, since pardon for all sin is elsewhere promised (1 Jn. 1:9), this warning must refer to those who utterly reject the Spirit's message. During the Savior's earthly ministry, those who rejected his miracles as works of Satan were guilty of this grievous sin because his message and claims were authenticated by the signs he performed by the power of the Holy Spirit (Mt. 12:22).
Today, his message and claims are authenticated by the Scriptures, which are a work of the Holy Spirit (Eph. 6:17). When someone utterly rejects God's Word, they place themselves beyond the only redemptive means available for their salvation.
In his early life, Paul was a blasphemer (1 Tim. 1:13), but his sins were washed away when he submitted to Heaven's saving plan (Acts 22:16).