The language of slavery is something to be incredibly careful with. It’s not something to use casually, or as a metaphor. It’s really not ok to describe things as slavery that really definitely aren’t slavery – doing so undermines the meaning of the word, which in turn may cause people to take the whole idea less seriously.
It’s important to talk about historical slavery and the ongoing impact that has in the world – both for those who remain disadvantaged and damaged by its impact on their ancestors, and for those who continue to benefit from the profits their families made.
There are other historical, oppressive systems that were horrible – indentured servitude being an obvious case in point. It’s not equivalent to Black experiences of slavery in America and people who want to talk about it on those terms often have a racist agenda, so it’s worth being clear that these are not the same thing. If a person who has entered this kind of contract is constantly facing new debt sources so that they can never escape from their ‘employer’ then we’re looking at something a lot closer to slavery. Very bad working conditions are not the same as slavery, but both historically and in the present there are those who truly push those lines.
Modern slavery exists and is defined in terms of being forced to do unpaid work. This often goes alongside human trafficking and organised crime. People who aren’t legally in a country, and who have no recourse to support are exploited hideously. I will never forget the Chinese cockle pickers in Morecambe bay who died in 2004, killed for someone else’s profits. Disregard for life is one of the hallmarks of slavery.
There is a grey area when it comes to people who are forced, through poverty into work that pays them so poorly they can never escape from it and that compromises their health – to a potentially fatal degree. A risky job where efforts are made to protect you is entirely different. However, if you could change job, if you have prospects, if you aren’t at risk of death then ‘wage slave’ isn’t a good term to use. Being trapped in oppressive capitalism is vile, but it isn’t slavery. Being owned by a company or a person so that you can only do what they permit you to do in all aspects of your life, is slavery. If you can choose, and if you can leave, you aren’t a slave.
Most importantly on the personal level, we need to stop describing ourselves as ‘slaving’ over things. We aren’t. Plenty of other, better language exists to describe hard work, considerable effort, personal suffering and discomfort. If what we’re talking about looks at all like a first world problem, a middle class problem, or a minor discomfort alongside our privilege, we should not be describing it in terms of slavery at all.
Druid Life 
There are lots of good reasons to be careful of the language we use. The problem with hyperbole is that we lose track of what we are actually saying as opposed to what we really mean. We say “this job is killing me” when it’s actually probably not, but the more we hear ourselves say it the more stress we take on over it. We tend to believe what we hear ourselves say, maybe not consciously but it does have an effect, and someone who calls their boss a slave-driver is causing themselves more antagonism against their boss the the situation really warrants.
That’s such an important point. Identifying a boss as a bully or someone abusing their power would also be a much better first move towards challenging that.