In vivo (Latin for "within the living") is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research. In vivo testing is often employed over in vitro because it is better suited for observing the overall effects of an experiment on a living subject.
A procedure performed in vitro is performed not in a living organism but in a controlled environment, such as in a test tube or Petri dish. Many experiments in cellular biology are conducted outside of organisms or cells; because the test conditions may not correspond to the conditions inside of the organism, this may lead to results that do not correspond to the situation that arises in a living organism.
Ad libitum is Latin for "at [one's] pleasure"; it is often shortened to "ad lib" or "ad-lib". The roughly synonymous phrase a bene placito ("at good pleasure") is less common but, in its Italian form a piacere, entered the musical lingua franca (see below).
In silico is an expression used to mean "performed on computer or via computer simulation. " The phrase was coined in 1989 as an analogy to the Latin phrases in vivo and in vitro which are commonly used in biology and refer to experiments done in living organisms and outside of living organisms, respectively.
Ex vivo means that which takes place outside an organism. In science, ex vivo refers to experimentation or measurements done in or on tissue in an artificial environment outside the organism with the minimum alteration of natural conditions. Ex vivo conditions allow experimentation under more controlled conditions than possible in the intact organism, at the expense of altering the "natural" environment.
Hibernaculum plural form: hibernacula (Latin, "tent for winter quarters") is a word used in zoology to refer to a place of abode in which a creature seeks refuge, such as a bear using a cave to overwinter. Insects may hibernate to survive the winter. The word can be used to describe a variety of shelters made by various animals, for instance, bats and snakes.
Titus Livius (59 BC – AD 17), known as Livy in English, was a Roman historian who wrote a monumental history of Rome and the Roman people, Ab Urbe Condita Libri, "Chapters from the Foundation of the City," covering the period from the earliest legends of Rome well before the traditional foundation in 753 BC through the reign of Augustus in Livy's own time.