Accruals

What does the word accrued or accruals mean? Is it true that they can be both what i mean is accrued income is the income which is earned but not received yet while the accrued expense is the liability which is incurred but not paid yet. Accrued income is the current asset whereas the accrued expense is the current liability? Is prepayment or accruals related to accrued income and accrued expense? Thank you!