“5-T” can mean different things depending on context:

• Informal abbreviation: sometimes used as shorthand for “5 times” or “five-ton” (rare and context-specific).
• Transportation: in some cities, “5T” can refer to a route or line number (like bus/tram line 5T).
• Chemistry/biology shorthand (rare): may appear in technical notes as a label or variant, but it is not a standard universal term like “2,4-D”.

Unlike “2,4-D” or “3D”, “5-T” is not a widely standardized term, so its meaning depends heavily on where you saw it.