Absorb

Absorb is a spell of the Restoration school of magic that lowers the target's Attribute and boosts your attribute by the same amount. The magnitude is the amount of atrribute points absorbed and the duration is the time for which the spell is effective. For health, magicka and fatigue absorption, the effect is permanent (ie, attributes won't reset after the duration is over.) and the duration indicates how long the spell will absorb that attribute.

Example:

Absorb Health 2 points for 10 seconds on Target: Each second after the spell takes effect, the spell takes 2 points of health from the target and restores your health by 2 points. After 10 seconds, the spell wears off and your health is a total of 20 points higher than before the spell and the target's health is 20 points less.

Absorb Agility 2 points for 10 seconds on Target: Each second after the spell takes effect, the target has 2 points less Agility and you have 2 points more Agility. After 10 seconds, your Agility reverts back to its original value, as does your target's Agility.

Essentially, absorbing health, magicka and fatigue is akin to stealing x amount every second for t seconds, whereas absorbing Skills or Attributes is akin to borrowing x amount for t seconds and giving x amount back after t seconds have passed.