Sanderson's (Porphyry) definition of Accidents

From Sanderson, Logicae, I, 5. (drawing from Porphiry's Isagoge, Chap. V) 

I. Accident is what is absent or present without the destruction of the subject, as whiteness. It belongs to the Subject that substance that inheres the Accident, as the swan.

II. Accident is that what is contingent to be present or not.

III. Accident is that which is neither genus, nor species, nor difference, nor property but always inheres in the substance of things. From there that an accident is or not.

The number of accidents cannot be in diverse subjects. Either simultaneous, either successive. (DUBIOUS)

Accidents are: Separable: those that can be separated from its subject, like cold from water.
Inseparable: those cannot be separated but intellectually, like fluid from water.

A very interesting addition to this list is afforded by Howell's (p.19) commentary of Thomas Wilson's Rule of Reason in which nine are the concepts of accident.

1. Quantity
2. Quality
3. Relationship
4. Action (Manner of doing)
5. Passion (suffering)
6. When
7. Where
8. Location ("settelling")
9. Habit

References

Howell, Logic & Rhetoric in England 1500-1700. Russell and Russell,