What defines a Protestant?

This question arose out of a conversation I had with my husband a few days ago. It came from reading this article: http://www.telegraph.co.uk/news/religion/10176190/Archbishop-Justin-Welby-I-was-embarrassed.-It-was-like-getting-measles.html in which speaking in tongues is described as a Protestant practice. My husband is Dutch, and tells me that in the Netherlands speaking in tongues is not considered a Protestant practice at all and Christians at the Charismatic-Pentecostal end of the spectrum are almost perceived as not being Protestant but rather a nominal divergence of it. 

This is not the case for Protestant churches in New Zealand, some of which practice and encourage tongues and other practices that could be considered “happy-clappy.”

It is also very different from my understanding of Protestant. As I see it there are three main strands of Christians: Catholic, Orthodox and Protestant. The Catholic and Orthodox Churches split in AD 1054 after a long period of troubled relationships, partially over the addition of the Latin word filioque into the clause about the Holy Spirit in the Nicene Creed by the western church (Catholic). This change was rejected by the eastern (Orthodox) church. In the east the Spirit proceeds from the Father, while in the west he proceeds from the Father and the Son.

In 1517 Martin Luther triggered the Reformation with his 95 theses in which he argues against the practice of indulgences (buying forgiveness from the church) as corrupt and unbiblical. The Protestant Christianity that came out of the Reformation was built on the basis that justification is by faith alone, and not faith and works as Catholic practices at the time indicated (as seen in indulgences). They also give the Bible the place of primary authority (instead of the Pope), and believe in a priesthood of all believers (not just ordained priests). It also limited the sacraments to two (communion and baptism) instead of seven (baptism, confirmation, Eucharist, penance, unction, holy orders and matrimony). 

It is this historical basis that has become my basis for defining Protestants as almost every Christian who is not Catholic or Orthodox. As a result my idea of a Protestant is very diverse (including Anglican, Methodist, Reformed, Lutheran, Baptist, Presbyterian, Charismatic, Pentecostal and Congregational to name a few of those prominent in western countries).
The discussion I had concerning speaking in tongues as a Protestant practice (or not) has started me wondering: how do other people (who perhaps haven’t been taught the historical background as I have) define a Protestant today?

So my question to you is: how do you define Protestant?

Please feel free to leave your thoughts and ideas in the comments below.