Fleeting vowels in к stems

The stems -ок-, -ёк-, and -ек- are highly productive in Russian; "productive" in this case means that they are still used to make new words in Russian. These stems have several uses:

• They are used to make diminutives, that is words that add the idea of "little" to the root meaning. Thus угол "corner" becomes уголок "little corner," голова "head" becomes головка "little head," and ухо "ear" becomes ушко "little ear."
• Sometimes the suffixes are added to a word that is either not gender-specific or is male-specific in order to make a female-specific word. Thus сосед "neighbor" is used when referring to a neighbor who is either male or whose gender is not yet specified in context, whereas соседка means specifically a female neighbor.
• Sometimes the suffixes simply make a noun without any diminutive meaning, e.g. ошибка "mistake".