The funds earmarked by an investor for the sole purpose of speculation. This capital is often associated with extreme volatility and a high probability of loss. Most speculators have short-term investment horizons and often use high degrees of leverage in their efforts to obtain profits.
Taobiz explains Speculative Capital
Given the above average probability of loss in speculative trading, it is critically important to exercise good risk management and not become emotionally attached to a certain trade. It is not uncommon to see novice investors hold onto a position until it loses nearly all of its value. Given their limited experience, rookie traders should regard all their tradable capital as speculative capital. In other words, they should only invest whatever amount of money they can afford to lose without their way of life being materially affected.