Math Words that Start with L: Definitions, Examples & Visual Guides for Students

Last updated: 12/08/2025

Math vocabulary is the key to understanding concepts — and the letter L is home to some of the most important terms in mathematics. From Linear equations that build the foundation of algebra, to Limits and Logarithms that drive calculus, learning these terms can boost confidence and problem-solving skills.

This guide is designed for elementary through calculus-level students and teachers, offering clear definitions, formulas, visual descriptions, real-world examples, and common mistakes to avoid.

The “Big Three” L Math Words

Deep explanations for the most essential L-words in math.

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1. Linear Equation

A linear equation is an equation whose graph forms a straight line.
Formula (slope-intercept form):
y=mx+by = mx + by=mx+b

Example:
If your phone plan charges 💵10/month plus 💵5 per GB used, the total cost can be modeled as
C=5x+10C = 5x + 10C=5x+10
where x is data used in GB.

Why it matters:
Linear equations appear everywhere — pricing models, speed/time problems, finance, and data trends.

2. Logarithm

A logarithm tells us the exponent needed to produce a number from a base.

Definition (snippet-friendly):
A logarithm answers the question: to what power do we raise a base to get a number?

Notation:
$log_b a = c iff b^c = a$

Example:
$log_2 8 = 3$
because
23=8.2^3 = 8.23=8.

Why it matters:
Logarithms are used in earthquakes (Richter scale), sound intensity, pH levels, and computing.

3. Limit

A limit describes the value a function approaches as the input approaches a number.

Notation:
l $lim_{x to a} f(x)$

Real-Life Example:
As you drive closer to a stop sign, your distance to it approaches 0 (even if speed varies).

Why it matters:
Limits are the foundation of calculus — including derivatives and integrals.

Geometry Math Words (Visual Focus)

Line

A line extends infinitely in both directions.

Line Segment

A line segment is a part of a line with two endpoints.

Ray

A ray begins at one point and extends infinitely in one direction.

Lateral Area

Lateral area is the surface area of the sides of a 3D figure (excluding bases).

Math Words that Start with L: Definitions, Examples & Visual Guides for Students - WuKong Edu Blog

Locus

A locus is a set of points that satisfy a rule (e.g., points equidistant from a center form a circle).

Arithmetic & Algebra Related L Math Words

Key Terms

Term	Short Definition	Example
Least Common Multiple (LCM)	Smallest shared multiple of two numbers	LCM(6, 8) = 24
Like Terms	Terms with same variable and exponent	2x + 3x are like terms
Leading Coefficient	The coefficient of the highest-degree term	In 5x³ + 2x², LC = 5
Less Than (<)	Relationship where one number is smaller	3 < 5

Comparison Table: Like vs Unlike Terms

Like Terms	Unlike Terms
Same variable + exponent	Different variable or different exponent
Combine by adding/subtracting	Cannot combine directly
Example: 4x + 2x	Example: 4x + 2y

Advanced / Calculus Concepts (Quick Guide)

These terms appear in higher-level math:

L’Hôpital’s Rule – Method to evaluate limits of indeterminate forms using derivatives.
Local Maximum – A point where the function is higher than nearby values.
Linear Approximation – Using a tangent line to estimate function values.

Math Words That Start With L — Vocabulary Quick Table

English Term	中文	Pinyin	Simple English Definition	Typical Grade Level
Line	直线	zhí xiàn	A straight path extending forever in both directions	Grade 3–5
Line Segment	线段	xiàn duàn	A part of a line with two endpoints	Grade 3–5
Ray	射线	shè xiàn	A line that starts at one point and goes on forever in one direction	Grade 3–6
Length	长度	cháng dù	Measurement of how long something is	Grade 1–3
Less Than (<)	小于	xiǎo yú	A comparison showing one value is smaller than another	Grade 1–3
Least Common Multiple (LCM)	最小公倍数	zuì xiǎo gōng bèi shù	The smallest number that two or more numbers divide into evenly	Grade 4–6
Like Terms	同类项	tóng lèi xiàng	Terms with the same variable and exponent	Grade 6–8
Linear Equation	线性方程	xiàn xìng fāng chéng	Equation that graphs as a straight line	Grade 7–10
Linear Function	线性函数	xiàn xìng hán shù	A function with constant rate of change (slope)	Grade 8–10
Leading Coefficient	最高次项系数	zuì gāo cì xiàng xì shù	Coefficient of the highest-degree term in a polynomial	Grade 8–11
Logarithm	对数	duì shù	Inverse of exponentiation; asks what power makes a number	Grade 10–12
Limit	极限	jí xiàn	The value a function approaches as input approaches a number	Grade 11–12
Local Maximum	局部最大值	jú bù zuì dà zhí	A peak point higher than nearby values on a graph	Grade 11–12
L’Hôpital’s Rule	洛必达法则	luò bì dá fǎ zé	A method using derivatives to evaluate limits	Grade 11–12+
Lateral Area	侧面积	cè miàn jī	The surface area excluding bases of 3D solids	Grade 6–8
Line of Symmetry	对称轴	duì chèn zhóu	A line dividing a shape into two mirror halves	Grade 4–6
Locus	轨迹	guǐ jì	Set of points following a rule or condition	Grade 9–12

Conclusion

Learning vocabulary is one of the fastest ways to improve in math. Knowing what terms mean, especially foundational ones like Linear, Limit, and Logarithm, helps students solve problems with confidence and recognize patterns across grade levels.

Vocabulary builds understanding consistent practice builds mastery. If you want your child not only to learn math words, but also to apply them in real problem-solving, competitions, and logical thinking, WuKong Math can help.

WuKong’s online math enrichment classes support Grades 1–12, covering arithmetic foundations, algebra, geometry, AMC/Math Kangaroo competition training, and more.

🌟 Click here to book a FREE trial lesson and start leveling up math skills the smart way!

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Suitable for students worldwide, from grades 1 to 12.

Get started free!

Demi | WuKong Math Teacher

I am an educator from Yale University with ten years of experience in this field. I believe that with my professional knowledge and teaching skills, I will be able to contribute to the development of Wukong Education. I will share the psychology of children’s education and learning strategies in this community, hoping to provide quality learning resources for more children.