1. (noun) a quantity that does not vary

• constant quantity
• invariable

2. (adjective) unvarying in nature

• changeless
• invariant
• unvarying

3. (adjective) uninterrupted in time and indefinitely long continuing

• ceaseless
• incessant
• never-ending
• perpetual
• unceasing
• unremitting

1. (noun) a quantity that does not vary

• parameter
• parametric quantity

2. (noun) a number representing a quantity assumed to have a fixed value in a specified mathematical context

• avogadro number
• avogadro's number
• boltzmann's constant
• c
• light speed
• speed of light
• coefficient
• constant of gravitation
• g
• gravitational constant
• universal gravitational constant
• constant of proportionality
• factor of proportionality
• cosmological constant
• equilibrium constant
• gas constant
• r
• universal gas constant
• hubble constant
• hubble parameter
• hubble's constant
• hubble's parameter
• ionic charge

1. (adjective) unvarying in nature

• invariable

2. (adjective) steadfast in purpose or devotion or affection

• staunch
• steadfast
• unswerving
• unfailing
• unflagging

3. (adjective) uninterrupted in time and indefinitely long continuing

• continuous
• uninterrupted

1. (adjective) steadfast in purpose or devotion or affection

• faithful
• invariable
• stable
• unchangeable

1. (noun) a quantity that does not vary

• quantity

2. (noun) a number representing a quantity assumed to have a fixed value in a specified mathematical context

• number

1. (adjective) unvarying in nature

• changelessness
• constancy
• stability
• invariability
• invariableness
• invariance

2. (adjective) steadfast in purpose or devotion or affection

• constancy

3. (adjective) uninterrupted in time and indefinitely long continuing

• ceaselessness
• ceaselessness
• ceaselessness
• continuousness
• continuousness
• continuousness
• incessancy
• incessancy
• incessancy
• incessantness
• incessantness
• incessantness
• perpetuity
• sempiternity

1. (adjective) steadfast in purpose or devotion or affection

• inconstant