The definition of a slave = The legal property of another and is forced to obey them.
There are more than one valid definition of a slave:
Slave
- A person held in servitude as the chattel of another
- A person who is completely subservient to a dominating influence
Slave
1. One who is owned as the property of someone else, especially in involuntary servitude
2. One who is subservient to or controlled by another.
3. One who is subject to or controlled by a specified influence
Slave
1 (Especially in the past) a person who is the legal property of another and is forced to obey them
1.2 A person who is excessively dependent upon or controlled by something.
The Oxford dictionary puts the origin of the word as such: Middle English: shortening of Old French esclave, equivalent of medieval Latin sclava (feminine) 'Slavonic (captive)': the Slavonic peoples have been reduced to a servile state by conquest in the 9th century.
A lot of people may be more familiar with slavery as legal slavery in which a someone being reduced to a something by the means of becoming someone else's property in the eyes of that someone else or by the law but there are other forms of slavery besides legal slavery.