functional

1. (physiology, psychology) Characterizing functioning in environment, being symptoms that do not presuppose alteration of organic structure.Examples: "The clinical differentiation between functional and organic disease is at times difficult to establish, because, presumptively, in the beginning, at least, all organic disease is preceded by a physiologic perversion, that is, functional alteration, which may or may not be apparent with our present diagnostic limitations. […] Though benign rhythmic disturbances, such as premature contractions or paroxysmal tachycardia, do occur, it is notoriously difficult and still the subject of argument whether these may be called functionally benign or whether they may prove to have organic significance. […] The lack of opportunity for the medical student to observe the functional states in the medical school clinics and hospital practice, because of lack of space, or interest in their care in intramural teaching, is, I believe, a most forceful argument for a period of extramural practice under intelligent tutelage."; "In our study of participants aged 18–39, increasing age was associated with improved functioning in laundry task and overall social functioning, encompassing prosocial activities, recreation, independence–competence, and employment. […] However, several longitudinal and cross-sectional studies indicate that these improvements tend to plateau by the late twenties, and may decline as individuals transition into middle adulthood (Clarke et al., 2021; Smith et al., 2012; Tomaszewski et al., 2025). These patterns suggest that while functional gains may be observed through early adulthood, they may not be maintained beyond the early thirties. Therefore, longitudinal studies extending into middle and late adulthood are critically needed to clarify how trajectories of activities of daily living and social functioning evolve throughout the lifespan."

2. (mathematics) Of or relating to a function or functions.

3. (computing theory) Having semantics defined purely in terms of mathematical functions, without side-effects.Synonyms: pureAntonyms: imperative