Terumah means "contribution", since the Tabernacle was constructed from contributions made by the Jewish people.
But why is the Parsha about God's house named after man's contribution?
Chasidic thought teaches that God created the world because He had a plan, but the plan contains a clause:
The plan is that God's presence be revealed in the world.
The clause is that this should occur by the efforts of man,
At the giving of the Torah, God stated His plan, He taught us that we can reveal His presence in the world by performing the mitzvos.
But, at that moment, everything had come from God.
With the construction of the Tabernacle, God's clause began to be implemented. Now, man had made an effort to help God's plan reach fruition.
It is for reason that our Parsha, which speaks of God's house, is named after man's contrition. For God's house could only be complete when His clause for human involvement was adhered to.
A problem with this Parsha is that it appears, at first glance, to be obsolete. The Tabernacle was a temporary structure, which was superseded by the Temple in Jerusalem. So why do we have to read about it at all?
The tabernacle possessed one advantage which the Temple did not have:
The uniqueness of the Tabernacle is that it broth its contribution to the farthest of place, the desert.
So we read Parshas Terumah, year after year to remind us of the need to bring Judaism to the most distant places.
(Based on Likuteu Sichos, vol. 21, pp. 146ff)