Something objectively and comparably strong,...can't really judge potency on memory imo ....it has to be by comparison, you know something is strong when it truly differentiates,...back in the day when i was still growing i would smoke potential keepers over a few weeks to compare them .....allot of the highs would just melt into one another, but the very potent strains would always stand out .....be that narcotic highs or euphoric highs ,.... altho high strength didn't always mean keeper .....i was more into the 'vibe' .. The quality of that high rather than its strength