Differences between words, phrases and idioms

this entry will illuminate similarities and distinctions between usage
a goal of this article is to provide a rule for idiomatic usage
- idiomatic means use of a word or phrase out of practice, outside of any particular rule
  - i.e., we use the word or phrase because we use it
  - = a circular, non-rules-based and inadequate explanation for word and phrase choice
rules-based syntax (word choice) is more effective than pure memorization of word context and phrases
See also:
- Parts of speech
- List of word parts of speech & their grammar rules

Here for difference between

A-C

at once = immediately or now, but an also mean "simultaneously"
- ex. "I'll get to that at once"
- v. "I'll do both things at once"
right away = immediately, but can also indicate "next" or "soon"
- ex., "I'll get to that right away"
- v. "I'll get to that right away, as soon as I'm done with this first thing"

near = close but not next to
nearby = closer than "near"
by = next to, whether or not particularly close; also means to go past something
next to = adjacent to
on = within, touching, or attached to the top of
ex.:
- "I drove near the supermarket" = I was near but not close to the supermarket, I was in its vicinity
- "I drove by the supermarket" = I directly passed the supermarket
- "I drove next to the supermarket" = I passed the supermarket, whether directly or not