You will notice that some common terms are deprecated in the KnowledgeBase. (Wikipedia definition of deprecation.) These are concepts we recommend that you avoid because they are often misunderstood, leading to bad technique, and sometimes because a more clear term and technique has been developed.

Also avoided:

• Physics: If “center of gravity” was as obvious as people make it out to be, everyone would have much better balance. This is an abstraction that most people can’t experience.
• Abstractions (such as the term ‘axis’) Abstracting is part of how we think. We generalize and theorize and simplify as we categorize an theorize our world. Some abstractions are very useful, others are confusing. In the case of tango, many abstractions take us further from physical experience, and are therefore not helpful.
• Metaphors (cats, surfing, water…). One of the few metaphors I use is the “arch” of connection. I tried not to use it, but found that students were organically introducing this word to describe their experience.

Here’s a list of deprecated terms:

• out-of-axis - In anatomy, the axes of a body are defined without any reference to the position of the body or its relation to the floor or gravity. This concept has nothing to do with balance, function, or movement. The way dancers use this term is not accurate. The scientifically correct concept to which dancers are referring is ‘orthostasis’, but even scientists […]
• enganche - In Castellano, a gancho is a hook. Enganche means to hook something. This term is used in tango to refer to a wide variety of hooks, from double-gancho to back cross. Since enganche does not refer to a particular movement, it is deprecated. Please see the individual movements.
• Compression - The anatomical term for what is sometimes called compression (deprecated) is co-contraction.
• Entrada - Entrada (deprecated) is a weak sacada.
• Mirror system - Former replacement for ‘parallel-system’, both now deprecated in favor of pace-system. When walking front and back, we need two concepts to describe precisely the improvisational possibilities. The first is where we are walking. We can walk on two, three, or four tracks. The second concept is which pair of legs move simultaneously. When both partners […]
• Core - Core (deprecated) is a term exercise professionals use to refer to a group of muscles which work together to stabilize the body during movement. Since the complex of core muscles are very powerful, exercise physiologists have come to recommend that the core be activated first whenever we undertake movement. In this way, more vulnerable muscles […]
• Frame - The purpose of frame (deprecated) is to maintain perfect connection. In place of frame, we build an arch of connection. The embrace completes the arch. We use external rotation of the shoulder joints (contracting the rotator cuff muscles) and gentle contraction of the triceps to stabilize the elbow joints while allowing for agility in adjusting to […]
• Cross-system - Cross-system is deprecated, as it is too easily confused with the movement called the cross. It is replaced with the accurate term for describing this four-legged gait, ‘trot-system’ and with the geometry of gait on tracks in the floor.  
• Parallel - The term parallel is used in several ways. Walking in parallel system (deprecated) refers to walking on two or four tracks in pace-system. We reserve the term ‘parallel’ as it is used in contemporary ballet to describe the orientation of the hips and feet.
• Collapse - The term ‘collapsed hips’ has been deprecated. The anatomical term is ‘drop hip’ and the cause is internal rotation of the hip joint. Internal rotation of legs and arms is to be avoided. External rotation engages the hip and shoulder stabilizers (piriformis and rotator cuff) to support the joints. and enables the muscles to work […]
• Oppositional power - Oppositional power or force is deprecated. We adjust the position and quantity of muscle contraction in our arcs to maintain the arc of connection at all times. The maximum muscle power is provided by co-contraction.
• Suspension - People use the term ‘suspension’ to describe is a wonderful feeling of floating and timelessness. It facilitates smooth transitions, provides space-time for adornos, and feels great. The biomechanics for creating suspension (deprecated) is the arch of connection (not your hands or shoulders, that just creates tension).
• Contra - (Disambiguation) Contra is used in two contexts. It is often used to teach walking. The contra walk is deprecated as it is often counterproductive. Similar to the term disassociation, contra is an instruction both imprecise and excessive. Arbitrary implementation of contra motion at the wrong point in the step weakens the body by causing internal rotation […]
• Axis - In anatomy, the axes of a body are defined without any reference to the position of the body or its relation to the floor or gravity. This concept has nothing to do with balance, function, or movement. The way dancers use this term is not accurate. The scientifically correct concept to which dancers are referring is ‘orthostasis’, but even […]
• Collect - Collect (deprecated) is a technique often taught to beginning dancers in which Revels are exhorted to grab their legs together at the end of each step. While we do indeed want the legs to pass close to each other for a moment between steps (with a sexy relaxation of the knee and ankle of the […]
• Disassociation - Disassociation (deprecated) is a term often used to teach tango, but its lack of precision results in bad technique. The first problem is that Disassociation is used to refer to two quite different things: torsion in the body, and separation between the embrace and the legs. Torsion in the body When we create torsion we […]
• Freeze - Freeze was one of the 2011 TangoForge 5 Competencies. It has since been deprecated. The purpose of a freeze is for the Mark to let the Revel know that you don’t want her to move from her current base position. This instruction should not be necessary as Revels should never leave their bases without being […]
• Tension - Tension (deprecated) is a vague term which is used to describe the gentle muscle contractions we need to keep our bodies connected (for example contraction of triceps muscle to keep the embrace taut) intense muscle contractions we need to support dramatic moves like rebvolcada and colgada excess habitual muscle contractions which block communication.. What is […]
• Energy - Our muscles burn fuel for the energy to contract. Muscles do not create energy (deprecated), they use energy. These contractions create power, which is expressed as force and velocity.   Wikipedia Power is created through different kinds of contractions (concentric, eccentric, isometric). Force, at a velocity, is transmitted to the partner. The structure of the arch of […]