Tank

Noun: Tank
Sometimes also humorously referred to as "meatshield," Tank is a term that denotes a warrior. Warriors are called tanks because they have the highest armor level in the game and as such have the highest resistence to damage. The antonym of a tank is a "squishy". Tanks can be one of two types:

Offensive Tank
A warrior specialized in heavy damage dealing. His/her primary focus is engaging the biggest threat in the enemy and quickly rendering it lifeless. His tools include knockdowns, bleeding and deep wounds. An Offensive Tank's biggest fear is hexes like Empathy that cause an attacker to lose health as well as negative conditions like Blindness that cause an attacker to miss.

Defensive Tank
A warrior fortified with all possible defensive tactics to soak up as much damage. A Defensive Tank will charge the enemy but will focus mostly on engaging the frontline of the enemy and keeping them busy fighting him/her. Defensive Tanks will use shields, stances and -if applicable- Protection Prayers to minimize damage inflicted upon them. They can take quite a long while to kill. Defensive Tanks can be used as booby traps using AoE spells that are centered on the caster such as Symbol of Wrath, or Balthazar's Aura.

To tank
Standing still and taking a beating from enemies instead of running away or kiteing. Tanking is often used in PvE to make the healer's life easier (only one person to concentrate on). Tanking is especially effective in combination with Protection spells and stances.