Following is the definitions,
In an average 28 day menstrual cycle, ovulation usually occurs on day 14, with day 1 being the first day of menstrual bleeding. If a woman has cycle lengths that are shorter or longer than 28 days, then the day of ovulation will usually be 14 days before her next period. So if she has a 26 day cycle length, then her ovulation should be on about day 12 and if she has a 32 day cycle, the ovulation is about day 18.
The length of time it takes a follicle to mature and ovulate is somewhat variable in different women (and in different cycles in the same woman), but the number of days from ovulation to the next period is much less variable and should be close to 14 days in everyone.

Developing follicle during a 28 day cycle with ovulation on day 14
Menstrual cycle days are shown at the bottom
Some women do not properly develop and release a mature egg every month - they do not ovulate regularly. We call this anovulation (lack of ovulation) - or oligoovulation (infrequent or irregular ovulation).
Some women never develop and release an egg without medication - we say they are anovulatory. These women have no menstrual periods for several months or years at a time. The medical term for this is amenorrhea - lack of menstrual periods. Often, when they do have a period it is quite heavy. In some cases, they may even require medical attention because of the degree of blood loss.
Some women ovulate occasionally (oligoovulation), for example, several times a year. They will often need medication to stimulate more regular egg development and ovulation to increase the chances for pregnancy.
Diagnostic testing for ovulation disorders
Usually blood testing and ultrasound studies of the ovaries at various times of the menstrual cycle can clarify whether ovulation is occurring. BBT Chart is another tool we use to estimate ovulation work.