This Latin phrase translates to "from the beginning." It is used to indicate that an experiment (typically computational) was performed from first principals. The phrase can be used as an adjective (ex. "She performed an ab initio experiment.") or an adverb (ex. "Her experiment was done ab initio.").

This is an abbreviation of the Latin phrase et alii meaning "and others." It is often used to shorten a list of three or more author, either in text or in a reference section (ex. "Smith, et al. (2012), demonstrated...." as a in-text reference to a paper by Smith, Jones and Knightly.).
It is common for novice writers (and veterans alike) to fail at correctly punctuating this abbreviation. Just remember, et is a complete word. An easy reference for this is the ampersand (&). This typographic shortcut was one of the earliest derived symbols to appear in English, particular in signage (ex. "Smith & Sons Plumbing"). Below are three ampsersands from common fonts. The first is from Times New Roman, drawn in 1931 for the London Times. The second is from Georgia, released in 1996 for reading on computer screens. Both of these ampersands look very traditional, not unlike the treble clef mark, in these serifed Roman fonts. The third ampersand is from the humanist font Trebuchet MS, also released in 1996 and designed for screen reading. Here the ampersand is a clear ligature of "E" & "t", reflecting the origin of the ampersand—the Latin et. The word alii is the Latin for other (plural, gender neutral), used to describe a group of all men or of mixed gender (aliae for a group of all women). Thus this word is abbreviated, and followed by a period.

This Latin phrase translates to "of life." It is used to indicate that an experiment was done in a way that was very close to the living system. This might be an experiment in a cell-free extract where a wide variety of cellular components are still present, but the system is no longer a viable organism. The phrase can be used as an adjective (ex. "She performed an ex vivo experiment.") or an adverb (ex. "Her experiment was done ex vivo.").

This pseudo-Latin phrase means that the entire experiment was done with a computer. It is another way of saying this is a calculation, either a simple computation or a large, complex simulation. The phrase can be used as an adjective (ex. "She performed an in silico experiment.") or an adverb (ex. "Her experiment was done in silico.").

This Latin phrase translates to "in place." It is used to indicate that an experiment was performed in the larger context of the organism. This type of experiment is often done to show the spatial or temporal distribuion of some factor or molecule throughout an organism. The phrase can be used as an adjective (ex. "She performed an in situ experiment.") or an adverb (ex. "Her experiment was done in situ.").

This Latin phrase translates to "in or within glass." It is used to indicate that an experiment was performed with purified components. This phrase quite literally states that the experiment was done in a test tube (or equivalent). The phrase can be used as an adjective (ex. "She performed an in vitro experiment.") or an adverb (ex. "Her experiment was done in vitro.").

This Latin phrase translates to "in or within life." It is used to indicate that an experiment was done in a complete living system (not the typical biochemical approach). The phrase can be used as an adjective (ex. "She performed an in vivo experiment.") or an adverb (ex. "Her experiment was done in vivo.").