Un-

Un- is a prefix which GURPS uses in several cases, and is notable as not actually describing absolute situations, and more roughly just means "less". For example:
*Uncontrollable Appetite actually can be controlled in most cases by passing a Self Control roll
*Unfit clearly is not a complete lack of fitness since there is a further Very Unfit level beyond it, it refers to a compared-to-baseline relationship
*Unhealing has a "Partial" level which DOES allow healing via stuff like Vampiric Bite and even the "Total" level can have HP restored via surgery or repairs
*Unkillable at the first level CAN be killed by going below -5xHP. It basically just means "don't bother with the HT check, they're passed automatically".
**the 2nd and 3rd levels are more true-to-form although it is possible to kill people with them using Negated Advantage to remove them, or make them functionally indefinitely dead by using Unhealing attacks
*Unluckiness is not an absolute lack of luck (you can still roll a critical success, foes can crit fail when targeting you) but rather just means a daily unfortunate event will happen
*Unnatural Features are subjective (what is and isn't 'natural'?) and probably means more like "unusual" or "inhuman" or "not in any observable mammal"
*Unusual Biochemistry and Unusual Background similarly could be subjective things, referring to what is "usual" for a specific species or setting/culture, which may be different elsewhere
==Related==
*Indomitable uses a similar prefix "in-" as Unfazeable. The latter is immune to Intimidation while the former is immune to that and all social skills in general EXCEPT when the user has an appropriate empathy.
*Fearlessness uses a similar -less suffix, but unlike Unfazeable is not an immunity to Fright Checks, only a bonus to Will when rolling to resist them
category:rules