Glossary

The process of spreading a loan into equal periodic payments. Early payments are mostly interest; later payments are mostly principal.

Annual Percentage Rate. The yearly cost of borrowing expressed as a percentage, including interest and most fees. APR lets you compare loans on an apples-to-apples basis.

Annual Percentage Yield. The effective yearly return on savings, accounting for compounding. A 5% nominal rate compounded monthly yields an APY of about 5.12%.

Body Mass Index. Weight (kg) divided by height (m) squared. A screening tool for weight categories, not a direct measure of body fat.

Basal Metabolic Rate. Calories burned at complete rest to maintain essential functions. Typically 60-75% of total daily calorie needs.

The proportion of total body mass that is fat tissue. Healthy ranges are roughly 10-20% for men and 18-28% for women.

Compound Annual Growth Rate. The constant yearly rate that would take an investment from its initial value to its final value. CAGR = (Final / Initial)^(1/years) − 1.

Three temperature scales. Celsius (water freezes at 0°, boils at 100°) is global standard. Fahrenheit is US-specific. Kelvin is the absolute scale used in science.

Interest calculated on both the principal and previously earned interest. The snowball effect that makes long-horizon investing powerful.

A range of values, derived from sample data, that is likely to contain the true population parameter with a specified probability (commonly 95%).

A statistical measure of how two variables move together. Ranges from −1 (perfect negative) to +1 (perfect positive). Zero means no linear relationship.

For a quadratic equation ax² + bx + c = 0, the value b² − 4ac. Positive → two real roots; zero → one repeated root; negative → two complex roots.

Equated Monthly Installment. The fixed monthly payment on an amortising loan that covers both principal and interest.

The product of all positive integers up to n, written n!. 5! = 5 × 4 × 3 × 2 × 1 = 120. Used in combinatorics.

Greatest Common Divisor / Factor / Highest Common Factor. The largest integer that divides two or more given numbers evenly.

Least Common Multiple. The smallest positive integer that is divisible by each of the given numbers.

The inverse of exponentiation. log_b(x) = y means b^y = x. log (base 10) is common in science; ln (base e) is common in calculus.

Loan-to-Value ratio. The loan amount divided by the appraised value of the asset. Mortgages with LTV above 80% usually require PMI.

Macronutrients: protein, carbohydrates, and fats. The three energy-providing nutrient categories in food.

The arithmetic average of a set of numbers: the sum divided by the count. Sensitive to outliers.

The middle value of a sorted dataset. Robust to outliers; a better "typical value" than the mean for skewed distributions.

The mass of one mole of a substance, expressed in grams per mole (g/mol). Equals the element's atomic weight for pure elements.

A symmetric bell-shaped distribution defined by its mean and standard deviation. The foundation of many statistical tests.

V = I × R. The voltage (V) across a resistor equals the current (I) flowing through it multiplied by its resistance (R).

The probability of observing data at least as extreme as the observed sample, assuming the null hypothesis is true. Conventionally, p < 0.05 is considered statistically significant.

A measure of acidity. Scale 0-14; pH 7 is neutral, below is acidic, above is basic. Defined as -log₁₀[H⁺].

The ratio of a circle's circumference to its diameter, approximately 3.14159265. An irrational number with no repeating decimal pattern.

The original amount of money borrowed (in a loan) or invested (in savings). Interest accrues on the principal.

The motion of an object thrown or launched under gravity alone. Horizontal motion is uniform; vertical motion is uniformly accelerated.

For any right triangle: a² + b² = c², where a and b are the legs and c is the hypotenuse.

The SI unit of angular measure. 2π radians = 360°. Used in calculus and physics where polynomial forms are cleaner than degrees.

Return on Investment. The ratio of net profit to the cost of an investment, expressed as a percentage.

A quick mental shortcut: divide 72 by an annual rate of return to estimate the years needed for an investment to double.

A way of expressing very large or small numbers as a × 10^b, where 1 ≤ |a| < 10. E.g., 6.022 × 10²³.

The digits in a measurement that carry meaningful information. 0.00520 has three significant figures; trailing zeros after a decimal count.

Interest calculated only on the original principal, not on accumulated interest. Often used for short-term loans.

Systematic Investment Plan. A fixed amount invested at regular intervals (typically monthly) into a mutual fund.

A measure of the dispersion of values around the mean. Low SD means values cluster tightly; high SD means they spread widely.

Total Daily Energy Expenditure. BMR multiplied by an activity factor (1.2-1.9) to estimate total daily calorie needs.

The duration of a loan or investment. Longer tenures reduce monthly payments but increase total interest paid.

The average of squared deviations from the mean. The square of the standard deviation; same information in squared units.

Value-Added Tax / Goods and Services Tax. A consumption tax collected at each stage of the supply chain and ultimately borne by the final consumer.

The number of standard deviations a value sits above or below the mean. z = (x − μ) / σ.