Here are a few of the most commonly used acronyms and terms. This list is by no means exhaustive. Please leave a comment below if you have something to add to this list.
This list does not include vendors or suppliers. I have been slowly compiling this list over the course of a few years. It is also printed at AussieHomeschool.

Acronyms

ACG is A Child’s Geography by Ann Voskamp
ACHOW is A Child’s History of the World (Hillyer)
AO is Ambleside Online, a free online CM based curriculum
ATW180Days is Around the Word in 180 Days
CE is Classical Education, usually using a Classical Curriculum
CM is Charlotte Mason.
ETC – Explode the Code
ETWHC is Educating the Wholehearted Child by the Clarkson’s
FAR is Far Above Rubies
FIAR is Five In A Row and BFIAR is Before FIAR
HEA – Home Education Association of Australia
HOW is Heart of Wisdom by Robin Sampson, also included is the HOWTA which is the HOW Teaching Approach
HWT – Handwriting Without Tears
LA is sometimes the unit study program called Learning Adventures or
LA is also Language Arts (the subject of studying English)
LLATL is Learning Language Arts Through Literature
MMM us Making Math Meaningful
MOH is Mystery of History by Linda Hobar
MUS is Math-U-See
RB is usually Ruth Beechick
SL is Sonlight
SM can be Singapore maths
SOTW is Story of the World (Bauer)
The 3 R’s and YCTYCS is for You Can Teach Your Child Successfully Grade 4-8 by Ruth Beechick
TT can be teaching textbooks
TTT or the Bluedorn’s is Teaching the Trivium by the Bluedorn’s.
TWTM is The Well Trained Mind by Susan Wise Bauer

General Abbreviations

• Afterschooling – Refers to supplementing a child’s learning after school. In other words, after a child attends regular public or private school all day, they engage in additional educational classes or activities supervised by their parents, tutors, or others.
• AP is usually the Authorised person from the BOS.
• BOS – Board of Studies
• Burnout is a term used to describe a parent or child who has become exhausted from the process of homeschooling.
• Carschooling – A term coined by Diane Flynn Keith to describe learning while riding in the car.
• Classical Education – A process of teaching children to learn based on developmental phases and educational principles developed by the ancients. For the primary years, children learn fact-based information. In the middle school years, children learn logic and reasoning, and in the high school period, children develop the art of abstraction and persuasion. Also referred to as “trivium-based.”
• CM – Miss Mason was a 19th century educator who believed that education should be based on great literature and the arts. She believed in a leisurely, self-directed style of education based on observation and reflection, often through discussion and journaling. Charlotte Mason education is based on a lifelong quest for knowledge and the skills.
• Copywork – This technique is used to help students learn to write — from the initial skill of forming alphabet letters, all the way through learning to write sentences, paragraphs, poetry and more. Once students have the ability to copy sentences and paragraphs, they usually copy excerpts from good/classic literature. The idea is that by copying, they learn the techniques of great writers that they can then apply to their own original writing.
• COS – Course of Study
• Course of Study – Refers to an outline of academic subjects to be covered by grade level such as: English, Math, Social Sciences, Science, Visual & Performing Arts, Health, Physical Education, etc. Each subject may be broken down into topics and sub-topics with references to the educational textbooks, workbooks, and other materials and resources that will be used for study. See World Book Encyclopedia’s Typical Course of Study for PreK-12.
• Curriculum – The materials used for a course, which can include a text-book, a teacher and grading guide, lesson plans, tests, and worksheets.
• DE – Distance Education Provider – A school that enrols homeschooling children or families and offers services and curriculum supportive of home education.
• Deschooling – Deschooling refers to the period of time, also called decompression, when students (and family) adjusts after leaving a traditional school setting. This period can range from a few weeks to an entire year, depending upon the student’s needs. It has been estimated that a period of deschooling be allowed according to the following: 1 month of deschooling for every one year that the child has been attending school.
• Eclectic Approach – A method of teaching that does not rely on any one approach but rather culls the best from multiple approaches.
• Lapbooking is a method of recording and tracking learning about a particular subject through the use of “foldables” which are then mounted and stored on file folders that have been refolded from a bi-fold form into a tri-fold form for better presentation. Often associated with Notebooking
• Learning Methods – Learning methods focus on the way a person best takes in and processes information.
• Learning Styles – This includes Auditory (learning through listening and talking), Visual (learning through seeing) and Kinesthetic/Tactile (learning through movement and touch).
• Notebooking – A method used to creatively journal or track homeschool studies and learning experiences by recording them on pages in notebooks or 3-ring binders.
• Relaxed homeschooling – Relaxed homeschooling is a similar term to Unschooling but takes more of an eclectic or blended approach, fitting curricula and resources to each student.
• School at Home – traditional schooling – A common beginning method of homeschooling in which a family attempts to simply recreate a conventional classroom education within their home. Many times this includes a boxed curriculum and can be somewhat of a rigid daily schedule.  Also referred to as Boxed curriculum or School in a Box or Pre-packaged Curriculum.
• Scope and Sequence – S & S An outline of skills and information to be taught, typically organised by grade level or by course. Provides information on what will be covered.
• Socialisation (The “S” Word) – Many homeschoolers are criticised as not providing appropriate socialisation, meaning the interaction found in a traditional school. As homeschoolers point out, traditional school’s artificial grouping by age, grade, and ability-level, is a dysfunctional and unrealistic situation compared to the socialisation of children within a family and more natural social groupings.
• Supplemental Resources – These are educational materials, field trips, and projects that are used to enhance the learning experience.
• Textbooks/ Workbooks– Textbooks are just one part of a package of resource materials that includes: a scope and sequence, an educators’ manual with teaching strategies, a student book with content explanations and examples, and a practice workbook. These packages usually offer a workbook or an enrichment workbook that focuses on higher level critical thinking skills.
• Unit Study/ Thematic study– A cross-curricular educational approach in which learning is focused around a central, common theme. For instance, a unit study on cars would teach the development and use of early cars (history), major highways (geography), different engine types (science),etc. Proponents of the unit study approach suggest that using unit studies allows students to immerse themselves in a topic and see that topic as a “whole,” rather than learning bits and pieces throughout their education.
• Unschooling/Natural Learning – Also known as student-led education, this is a teaching method in which students study those topics that interest them, rather than follow a pre-defined curriculum.