Chazal is an acronym for Hachamenu zichronam levrachah, "our Sages of blessed memory," and is used to refer to the sages of the Oral Law. Chazal lived as early as the era preceding the Maccabean revolt and up until the Arab conquest of the Mediterranean.
You might hear a rabbi referring to Chazal's view of women or asking, "What would Chazal do about global warming"? To discover whether Chazal were feminists or environmentalists, one would have study all the rulings, aphorisms and stories involving the sages and deduce from them an attitude or general position.
This is not a simple task as Chazal excelled at the art of the pithy expression and "felicitous abstract formulation", as Israel Abrahams, the translator of Ephraim Urbach's monumental work The Sages: their Concepts and Beliefs, put it.
The fact that we call the sages from over 2,000 years ago "our Sages of blessed memory" is a reflection of the fact that in traditional Judaism, the rulings and world view of the ancient scholars have contemporary relevance. When seeking a Jewish version of feminism or environmentalism, for example, it is important to traditional Jews that Chazal be part of the effort, that their insights guide us.
In engaging with the texts Chazal bequeathed us, we transcend the ages and continue a conversation that began with Abraham and takes on new meanings with every generation.