I saw this node and just had to give it a try. It'll probably end up being pretty similar to Mardy's though (although he/she only seems to have bothered with 50 words, for some reason).

Words for 'a' and 'the' are probably unecessary; the Romans, the Japanese, the Russians and others get along perfectly well without them. It might be possible to get along without 'yes' and 'no', instead using a verb to confirm or deny what has just been asked, but we'll include them to make things simpler. We also need 'and', 'but' and 'or', so that's 5.

Pronouns: I, we, you, he, she, it, they. That's seven, but we could cut it down to 5 by using the same word for 'he', 'she' and 'it', or even say 'it-man', 'it-woman' and 'it-thing' to indicate gender. Let's call it five pronouns, ten words total.

Prepositions: Up/on, down/under, to, of/from, in, out, before/in front of, left. 'Before' can be negated with 'no' to form 'after/behind', and 'left' to make 'right'. (Thanks to Apollyon for suggesting this.) That's 8 words, 18 total.

Verbs: Tricky to reduce it to just a few, but I think 'to be', 'to have', 'to do/make', 'to sense', 'to begin', 'to go/move/come', 'to eat/drink', 'to get/take', 'to put/give', 'to die/kill', 'to need', 'to like/love/want', 'to know', 'to think/remember', 'to speak/say' and 'to end' are about sufficient for starters. (The difference between 'to go' and 'to come' can be indicated with prepositions.) Negatives are formed using our word for 'no'. Verbs are intensified with repetition or the word for 'yes' (so 'to like-yes' or 'to like-like' would mean 'to love'.) We won't worry about tenses. Actually yes we will; 'to like-before-no' means 'to have liked' and 'to like-before' means 'to be going to like'. The difference between 'to kill' and 'to die' is that 'to kill' is transitive (the verb is performed on someone) and 'to die' is intransitive (it is not performed on anyone; you die and that's it). That's 33 words so far, total. We're making good progress.

Modal verbs can be 'must/should', 'might' and 'can'. That's really about all you need ('will' is just a verb in the future tense as shown above, and 'would' can be expressed with 'like to'. 36 total.

Numbers. Zero through ten, of course. After that we can rely on multiplication ('twenty-three' being 'two-ten-three' or 'six hundred and four' being 'six-ten-ten-four'.) As you can see, smaller numbers before bigger numbers means you multiply, smaller numbers after bigger numbers are added. We'll need thousand, million and billion as well, so fourteen numbers makes 50 words altogether.

Now for adjectives. We may be able to express colours. This is maybe overly complex but we can try basing them on colours. Colour-1 is red, colour-2 is purple, colour-3 is blue, colour-4 is green, colour-5 is yellow, colour-6 is white, colour-7 is grey, colour-8 is black. Notice the even colours are what you get when you mix the neighbouring odd numbers, with the exception of 6. We need orange, that could be number 9. 10 is brown, naturally. What's zero then? Transparent? Could 'yes' and 'no' be added to lighten and darken the colours (so colour-three-yes is light blue)? Maybe. This may be a bad idea, but it adds only one new word - the word for 'colour' - so we'll add it. Other adjectives are good, big, fast, light, strong, smart, safe, very, alive, old, easy, many, all, hot, high, same. We can negate them (yet again) with 'no', so we get bad, small, slow, etc. 16 adjectives, 66 altogether.

Question words such as 'what/who', 'why', 'where', 'how' and 'when' are required, as are 'this' and 'that'. I guess we can pluralise to 'these' and 'those' by repeating the word. Add these seven to our existing 66, and we've used 73 words.

This only leaves us with 27 nouns. Food, water/drink, person, animal, plant, family/relation, man, woman, vehicle, place, paper, clothing, other, fire, air, portal, surface, danger, sentence, sky, hole, container, space, power/electricity, tool, colour, day, thing. That's 27. So a book would be a 'paper-place-before-no-thing'. A mother would be an 'old-woman-family'; and grandmother a 'very-old-woman-family'. 'Trees' are 'big-old-plant-plant', the noun being repeated to pluralise it. A pink bicycle is a 'colour-one-yes small-power-no-vehicle', although you could get away with 'colour-one-vehicle' with some context.

Let's try a full sentence. Obviously this new language is going to take some learning, so you may want to know 'What to-be this small-sentence?' We just asked what a word meant with relatively little fuss. If the words are fairly short (with this few, they could be one syllable each) then it shouldn't be that difficult to communicate. Or should I say, 'It-thing should-no to-be very easy-no to-say-other'.

There you have it: a 100 word language which should cover most things you'd want to say. I can tell you're amazed.

(Good to "The Debutante", to-say-before-no to-I of portal small-sentences; I to-think-no-before-no all-day-day of they! And good to Apollyon to-say-before-no all to-I.)