Operational definition

Virginity is a social construct that denotes the state of a person who has never engaged in sexual intercourse. As it is not an objective term with an operational definition, social definitions of what constitutes virginity, or the lack thereof, vary. Heterosexuals may or may not consider loss of virginity to occur only through penile–vaginal penetration, while people of other sexual orientations often include oral sex, anal sex, or manual sex in their definitions of virginity loss. The term "virgin" encompasses a range of definitions, as found in traditional, modern, and ethical concepts. Religious rituals for regaining virginity exist in many cultures. Some men and women who practice celibacy after losing their virginity consider themselves born-again virgins.

There are cultural and religious traditions that place special value and significance on this state, predominantly towards unmarried females, associated with notions of personal purity, honour, and worth. Like chastity, the concept of virginity has traditionally involved sexual abstinence. The concept of virginity usually involves moral or religious issues and can have consequences in terms of social status and in interpersonal relationships. Although virginity has social implications and had significant legal implications in some societies in the past, it has no legal consequences in most societies today. The social implications of virginity still remain in many societies and can have varying effects on an individual's social agency.

In business, engineering, and manufacturing, quality – or high quality – has a pragmatic interpretation as the non-inferiority or superiority of something (goods or services); it is also defined as being suitable for the intended purpose (fitness for purpose) while satisfying customer expectations. Quality is a perceptual, conditional, and somewhat subjective attribute and may be understood differently by different people. Consumers may focus on the specification quality of a product/service, or how it compares to competitors in the marketplace. Producers might measure the conformance quality, or degree to which the product/service was produced correctly. Support personnel may measure quality in the degree that a product is reliable, maintainable, or sustainable. In such ways, the subjectivity of quality is rendered objective via operational definitions and measured with metrics such as proxy measures.

In a general manner, quality in business consists of "producing a good or service that conforms [to the specification of the client] the first time, in the right quantity, and at the right time". The product or service should not be lower or higher than the specification (under or overquality). Overquality leads to unnecessary additional production costs.

In physics, an observable is a physical property or physical quantity that can be measured. In classical mechanics, an observable is a real-valued "function" on the set of all possible system states, e.g., position and momentum. In quantum mechanics, an observable is an operator, or gauge, where the property of the quantum state can be determined by some sequence of operations. For example, these operations might involve submitting the system to various electromagnetic fields and eventually reading a value.

Physically meaningful observables must also satisfy transformation laws that relate observations performed by different observers in different frames of reference. These transformation laws are automorphisms of the state space, that is bijective transformations that preserve certain mathematical properties of the space in question.

Scientific modelling is an activity that produces models representing empirical objects, phenomena, and physical processes, to make a particular part or feature of the world easier to understand, define, quantify, visualize, or simulate. It requires selecting and identifying relevant aspects of a situation in the real world and then developing a model to replicate a system with those features. Different types of models may be used for different purposes, such as conceptual models to better understand, operational models to operationalize, mathematical models to quantify, computational models to simulate, and graphical models to visualize the subject.

Modelling is an essential and inseparable part of many scientific disciplines, each of which has its own ideas about specific types of modelling. The following was said by John von Neumann.

Dissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called particulate organic carbon (POC).

Dissolved organic matter (DOM) is a closely related term often used interchangeably with DOC. While DOC refers specifically to the mass of carbon in the dissolved organic material, DOM refers to the total mass of the dissolved organic matter. So DOM also includes the mass of other elements present in the organic material, such as nitrogen, oxygen and hydrogen. DOC is a component of DOM and there is typically about twice as much DOM as DOC. Many statements that can be made about DOC apply equally to DOM, and vice versa.

In physics, time is defined by its measurement: time is what a clock reads. In classical, non-relativistic physics, it is a scalar quantity (often denoted by the symbol ${\displaystyle t}$) and, like length, mass, and charge, is usually described as a fundamental quantity. Time can be combined mathematically with other physical quantities to derive other concepts such as motion, kinetic energy and time-dependent fields. Timekeeping is a complex of technological and scientific issues, and part of the foundation of recordkeeping.