The net amount of capital losses that aren't deductible for the current tax year but can be carried over into future tax years. Net capital losses can only be deducted up to a maximum of $3,000 in a given tax year. Any amounts exceeding $3,000 can be put toward offsetting capital gains in the current year or simply deducted in the next year.
Taobiz explains Capital Loss Carryover
Capital loss provisions can take some of the sting out of a losing investment, but investors must be careful of wash sale provisions, which prohibit repurchasing an investment within 30 days of selling it for a loss. If this occurs, the capital loss cannot be applied toward tax calculations, and is instead added to the cost basis of the new position, lessening the impact of future capital gains.