'Capitalism' was a term conceived by Marx and despite Marx and many other anti and pro-capitalist economists having much more to say on the subject, has always had a pretty straightforward definition of being an economy characterised by capital owners hiring wage labourers to generate returns on their capital. A definition sufficiently succinct to describe both the excesses of Silicon Valley and the grim poverty of the Industrial Revolution.
The definition relies on the assumption the distribution of capital is sufficiently unequal for workers to need/want to work for capitalists to earn wages and the market sufficiently free for it to be possible for capitalists to hire workers to generate returns. But both the Marxist arguments that capital must inevitably become so concentrated that capitalists won't need to pay workers above subsistence levels [until it leads to revolutions] and the free market economist argument that competition will resolve this [and pesky social democrats will ruin it] are firmly in the 'squishy' parts of the definition.
('Communism', which had competing definitions before Marx started writing about it, has always been a bit squishy...)
The definition relies on the assumption the distribution of capital is sufficiently unequal for workers to need/want to work for capitalists to earn wages and the market sufficiently free for it to be possible for capitalists to hire workers to generate returns. But both the Marxist arguments that capital must inevitably become so concentrated that capitalists won't need to pay workers above subsistence levels [until it leads to revolutions] and the free market economist argument that competition will resolve this [and pesky social democrats will ruin it] are firmly in the 'squishy' parts of the definition.
('Communism', which had competing definitions before Marx started writing about it, has always been a bit squishy...)