One of the first words I learned in Finnish was, believe it or not, laktoositon (lactose free; laktoosivaba in Estonian). Back a few years ago, before I was vegan, I used to buy lactose-free Finnish dairy products. I didn't know it at the time, but that -ton ending is the Finnish privative suffix.
There are other ways of 'without' in Finnish such as the use of the preposition ilman.
E: (ilma) suhkruta
The Finnish takes the adposition ilman and puts the noun in the PART while the Estonian adposition ilma, which is optional, puts the noun in the abessive with its characteristic ending -ta.
But back to the privative. Colloquial Finnish gives its form as =ttoMA. It kind of looks complex but what it basically means is that this is the deep-form of the suffix whereas its actual realization varies: -ton or -ttoma. The n of ton compresses the tt of -ttoMA to t.
You can add it to the 3rd infinitive of verbs. The Estonian equivalent here is -tu.
unexpected (odatta- 'waits, expects')
unmoving, still (liikku- 'moves')
unknown (tunte- 'knows')
In nouns the tt of the underlying stem compresses the consonants to its left as can be seen from the examples below:
apu ------ avuton
E: api ------ abitu
help ------ helpless
jalka ------ jalaton
E: jalg ------ jalutu
leg ------ legless
lanka ------ langaton
E: traat ------ traadita
wire ------ wireless
In the below examples you can see the realization -ttoma.
Mä en pidä unettomista öistä.
E: Mulle ei meeldi unetud ööd.
I don't like sleepless nights.
uusi versio Tuntemattomasta sotilaasta
E: uus versioon Tundmatust Sõdurist
a new version of the Unknown Soldier