From the Wikipedia article:

The Natural Semantic Metalanguage is an approach to semantic analysis based on reductive paraphrase (that is, breaking concepts/words down into combinations of simpler concepts/words) using a small collection of semantic primes. The semantic primes (below) believed to be atomic, primitive meanings present in all human languages.

Currently the following 61 primitives are recognized (in alphabetical order):

ABOVE, AFTER, ALL, BAD, BECAUSE, BEFORE, BELOW, BIG, BODY, CAN, DIE, DO, FAR, FEEL, FOR SOME TIME, GOOD, HAPPEN, HAVE, HEAR, HERE, I, IF, INSIDE, KIND OF, KNOW, LIKE, LIVE, A LONG TIME, MANY/MUCH, MAYBE, MOMENT, MORE, MOVE, (LONG), NEAR, NOT, NOW, ONE, OTHER, PART OF, PEOPLE/PERSON, THE SAME, SAY, SEE, A SHORT TIME, SIDE, SMALL, SOME, SOMEONE, SOMETHING/THING, THERE IS, THINK, THIS, TOUCH, TRUE, TWO, VERY, WANT, WHEN/TIME, WHERE/PLACE, WORD, YOU

After poking around a bit more, it looks like the 61 primitives in NSM correspond to 41 words in Toki Pona; some of the overlap comes from merging ideas such as "like" and "want", but the biggest change is use of compound phrases for things like places and times -- using "small time" for "brief" and "near me" for "here".

ala - NOT

ali - ALL

anpa - BELOW

ante - OTHER

ijo - SOMETHING/THING

ike - BAD

insa - INSIDE

jan - PEOPLE/PERSON; SOMEONE (jan wan)

jo - HAVE

kama - HAPPEN; AFTER (kama la)

ken - CAN; MAYBE; IF (ken la)

kute - HEAR

lili - SMALL, SOME

lon - THERE IS, TRUE

luka - PART OF

lukin - SEE

ma - WHERE/PLACE (or tomo for indoor places)

mi - I

moli - DIE

mute - MANY/MUCH, MORE, VERY

ni - THIS

nimi - WORD

pali - DO, LIVE

pilin - FEEL, THINK

pini - BEFORE

poka - NEAR; SIDE; TOUCH; HERE (poka mi); FAR (poka mi ala)

pona - GOOD

sama - THE SAME, KIND OF

sewi - ABOVE

sijelo - BODY

sina - YOU

sona - KNOW

suli - BIG; LONG

tan - BECAUSE

tawa - MOVE

tenpo - WHEN/TIME; A LONG TIME (tenpo suli); FOR SOME TIME (tenpo wa

+n); MOMENT (tenpo lili ni); NOW (tenpo ni); A SHORT TIME (tenpo +lili)

toki - SAY

tu - TWO

wan - ONE

wile - LIKE; WANT