(law) A litigant without an attorney.

(grammar) A tense that expresses an unbroken action continuing up to a certain time in the past. In English it is formed by using had been with a present participle.

past perfect continuous

(grammar) present perfect continuous

Future perfect continuous.

(grammar) A tense used to express an ongoing action completed after some time in the future. In English it is formed by use of will have been (or shall have been) and a present participle.

(grammar) A tense that expresses an unbroken action continuing at the present time, started in the past. In English it is formed by using have been with a present participle.

(baseball) A statistic which compares the total number of bases achieved by a batter over that batter's number of at bats.

(psychiatry) Any of a class of mental disorders characterized by ongoing rigid patterns of thought and action.

(art) perception of an object without known points of reference.