inefficient

As a noun dictionary

is a reference work with a list of words from one or more languages, normally ordered alphabetically and explaining each word's meaning and sometimes containing information on its etymology, usage, translations and other data.

As a verb dictionary

is (label) to look up in a dictionary.

As an adjective inefficient is

inefficient.

As adjectives the difference between weak and inefficient

is that weak is lacking in force (usually strength) or ability while inefficient is inefficient.

As adjectives the difference between inefficient and false

is that inefficient is inefficient while false is (label) one of two states of a boolean variable; logic.

As adjectives the difference between heavy and inefficient

is that heavy is (of a physical object) having great weight or heavy can be having the heaves while inefficient is inefficient.

As an adverb heavy

is heavily.

As a noun heavy

is a villain or bad guy; the one responsible for evil or aggressive acts.

As a verb heavy

is to make heavier.

As adjectives the difference between inefficient and undefined

is that inefficient is inefficient while undefined is lacking a definition or value.

As adjectives the difference between inefficient and deficient

is that inefficient is inefficient while deficient is deficient.

As an adjective inefficient

is inefficient.

As a noun null is

zero, nil; the cardinal number before einn.

Unequal is a related term of inefficient.

As adjectives the difference between unequal and inefficient

is that unequal is not the same while inefficient is inefficient.

Incommensurate is a related term of inefficient.

As adjectives the difference between incommensurate and inefficient

is that incommensurate is out of proportion (in size, degree or extent) with something else while inefficient is inefficient.