As an educational device, "one word substitutes" are essentially words that correspond to definitions instead of vice versa.
Examples would include:
Having no clear meaning - vague, ambiguous
Not able to be halted - unstoppable
Able to be changed - changeable, mutable
Occurring on and off - intermittent, transient
The word is newcomer.
Graphology
Blasphemy.
The word could be healthy for being free from infection.
I can give you several sentences.Use that ingredient as a substitution for the one you don't have.He is going in as a substitution for the quarterback.This is a substitution for the real thing.Margarine could be used as a substitution.
A+ Students: euphemism
Emigrate.
Euphemisms are more sensitive word substitutions.
examples of one syllable words
In basketball, a substitution is when one player goes in for another.
An ablaut is the substitution of one root vowel for another in a word, to reflect grammatical information, such as "get, gat, got".
Font substitution is when one font is used in place of another. This is typically done when the original font is unavailable or does not contain glyphs for the required characters. Adobe Reader, Microsoft Word, OpenOffice, and most recent browsers are capable of performing font substitution.