Intimidate is a keyword ability.
It is a static ability which restricts the types of creatures that can block a creature with intimidate. A creature with intimidate can't be blocked, except by artifact creatures and by creatures that share a color with it.
If Nora wishes to block the incoming Spirit, she can legally block it with the Sliver Construct, as it's an artifact creature, or the Undead Minotaur, as it shares a color with the Accursed Spirit, but not the Canyon Minotaur, as it neither shares a color with Accursed Spirit or is an artifact creature.
- 702.13a. Intimidate is an evasion ability.
- 702.13b. A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.
- 702.13c. Multiple instances of intimidate on the same creature are redundant.