Proprietary software developers who keep on redefining the words to make them
have the opposite meanings of those in the dictionary ("rights" in DRM,
"trusted" in "trusted computing", "pirates", etc.). Free software proponents
do not do that. Freedom just means what is written in the dictionary:
1. the state of being free or at liberty rather than in confinement or under
physical restraint.
2. exemption from external control, interference, regulation, etc.
3. the power to determine action without restraint.
4. political or national independence.
5. personal liberty, as opposed to bondage or slavery: a slave who bought his
freedom.
To sum up: being free is controlling one's own life. For software,
controlling one's own computing, not letting somebody else (the developer)
impose restrictions. The notion remains vague but, again, the free software
movement believes it has identified four freedoms that are fundamental for a
user to be in control of her own computing.