I think we need three concepts: speculation, carry and portfolio.
Speculation is the belief that price will change in the future, particularly of a commodity. Some speculations have positive carry, say if you can buy a building with a mortgage and let it out for more than the interest cost. Others have negative carry, like when you buy a gold future which costs more than the spot price or when you play at a roulette table where a zero makes the odds unfavourable. A dividend on a share is another example of positive carry. A portfolio is a set of speculations with positive carry where you hope that diversification will even out the winning and losing speculations to leave you holding the carry.
Portfolio is only one type of investment, but the latter term has a wide application, meaning anything you build in the present for a future payoff.