ple

Latin

fill, full

Variants:plepletplen

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About This Root

The root ple comes from Latin plēre, 'to fill,' and its twin adjective plēnus, 'full.' Both trace back to the ancient PIE root pleh₁-, 'to fill' — the same source that gives English the native word full and the prefix plus*. The whole family is built on one simple image: a container, and how full it is.

Start with an empty vessel and the prefixes tell you what happens to it:

- com- (completely) + plēre → complete: to fill it up entirely. Nothing missing, nothing left out — that's what 'complete' means. From there: completion (the act of filling up), incomplete (not yet full).
- de- (away, down) + plēre → deplete: to drain it back out. Your resources, your energy, the ozone layer — when something is depleted, the vessel has been emptied. Hence depletion.
- re- (again) + plēre → replenish (via Old French re-plenir) and replete: to fill it again, to make it full once more. A replenished stockroom; a book replete with examples.
- sup- (sup-, from below) + plēre → supplement: to fill in from underneath, to top up what's lacking. A dietary supplement fills a gap in your diet.
- com- + plēre → complement: to fill out and make whole. Two things that complement each other each supply what the other lacks. (Compare complementary colours — together they complete the spectrum.)

From plēnus 'full' comes the abundance branch: plenty, plentiful, and the Greek-flavoured plethora, which originally meant an over-full state (too much blood in the body) and now just means 'an excessive amount.' The little word plus ('more') is plēnus's close cousin too.

Two warnings. First, compliment (a flattering remark) is the same word as complement historically — both 'fill up / round out' — but split apart, so today complement = completes a whole, compliment = praises a person. They're a classic spelling trap. Second, and bigger: a huge set of look-alike words — complicate, imply, reply, comply, multiple, simple, ply — do not belong here. They come from Latin plicāre, 'to fold,' a completely different root (now housed under plic). 'Simple' = 'one-fold,' not 'one-fill.' If the idea is folding/bending, it's plic; if the idea is filling/fullness, it's ple.

From Latin plēre 'to fill' and plēnus 'full' (PIE *pleh₁- 'to fill'). A root of fullness and abundance: complete (fill up entirely), deplete (empty out), replenish (fill again), supplement and complement (fill up / round out), plenty, plentiful, plethora (overfull). Note: words from Latin plicāre 'to fold' (complicate, imply, reply, multiple, simple) belong to the separate plic root, not here.

Memory Tip

Think of a glass and how full it is. complete = filled up to the brim, deplete = drained empty, replenish = topped back up, plenty = overflowing. Every ple- word is about the level in the container. (Don't confuse it with plic = 'fold' — simple/reply/complicate live there.)

Core Words Deep Dive

The few words from this family worth telling in full — one by one.

complete

com- (completely) + plēre (fill) = 'filled up entirely.' This is the cleanest window onto the root: 'complete' literally means there's nothing left to fill in. The whole abundance vocabulary spins out from this filling image — completion is the filling done, incomplete is the filling unfinished.

deplete

de- (away) + plēre (fill) = literally 'un-fill,' to empty out. It's the exact opposite move from complete: instead of filling the vessel, you drain it. That's why we speak of depleted resources, depleted energy, ozone depletion — the tank has been run down.

supplement

sup- (from below) + plēre (fill) = 'to fill up from underneath,' to top up what's missing. A dietary supplement fills a nutritional gap; a salary supplement tops up income; a newspaper supplement adds extra pages. Always: something added to fill a shortfall.

plenty

Straight from plēnus 'full,' via Old French plenté 'abundance.' If a container is full, you have plenty — more than enough. The same plēnus gives plentiful and the over-full plethora, and is cousin to plus. Plenty is the everyday face of the 'fullness' branch.

complement

com- + plēre = 'to fill out, make whole.' Two things that complement each other each supply what the other lacks, completing the set. Historically the very same word as compliment (a praise) — they split, so now complement = completes, compliment = praises. A classic spelling trap.

Related Roots

plicConfusable

Identical-looking but unrelated. ple comes from plēre 'to fill' (complete, deplete, plenty). plic comes from plicāre 'to fold' (complicate, imply, reply, multiple, simple). Quick test: about fullness/level → ple; about folding/bending/layering → plic.

satSimilar

Both touch on 'enough / full.' ple is about a vessel being physically filled to capacity (replete, plenty). sat (from satis 'enough') is about being satisfied or saturated — having had enough. Filled to the top → ple; had enough → sat.