What is the meaning of the word "express"?

Definitions:

by express adverb
- please send the letter express
indicate through a symbol, formula, etc. verb
- Can you express this distance in kilometers?
not tacit or implied adjective
- My express wish is to be cremated.
obtain from a substance, as by mechanical action verb
- Italians express coffee rather than filter it
public transport consisting of a fast train or bus that makes only a few scheduled stops noun
- They caught the express to the big city.
send by rapid transport or special messenger service verb
- They expressed the letter to Florida.
to manifest the effects of a gene or genetic trait verb
- Many of the laboratory animals express the trait.
without unnecessary stops adjective
- an express train