-m,-sz conjugation

Sometimes this is presented as one of the three Polish conjugation types, sometimes as two of the four types (separately as -am,-asz and -em,-esz). Actually, being more specific makes a lot of sense, since the purpose of this section is to give you enough information so that nothing in this conjugation will surprise you later.

And I'll get to the details in a moment, but first things first: why is it called the -m,-sz conjugation? Because in this conjugation, the first person singular always ends in -m, and the second person singular always ends in -sz:

singular		plural
ja	-m	my	-my
ty	-sz	wy	-cie
on, ona, ono	-∅	oni, one	-ją / -dzą

If this is the first conjugation pattern you are learning, you may be happy to know that the forms for my and wy always end in -my and -cie respectively, in every conjugation. Also, the third person singular (on, ona, ono) is always formed by removing -sz from the second person singular form. Again, this works in every conjugation, in both the present tense and the perfective future tense (and in the past tense, we just remove -eś/-aś instead of -sz, but the past tense is a separate topic).

Now for the subgroups. Textbooks most often distinguish the -am,-asz conjugation for verbs ending in -ać, and the -em,-esz conjugation for verbs ending in -ieć. An example of such classification can be found in at polskinawynos.

However, since the distinction between -am,-asz and -em,-esz still leaves some irregularities unexplained, I'd like to suggest an alternative approach based on the third person plural ending: -ją versus -dzą.

-m,-sz ... -ją

based on the examples of czytać and rozumieć:

singular		plural
ja	czytam, rozumiem	my	czytamy, rozumiemy
ty	czytasz, rozumiesz	wy	czytacie, rozumiecie
on, ona, ono	czyta, rozumie	oni, one	czytają, rozumieją

This first group can contain verbs ending in both -ać and -ieć. It doesn't really matter which of the two endings the infinitive has, because both preserve the same vowel throughout the conjugation (expept for mieć - this one is irregular and in present tense it gets "a": ja mam, ty masz, on/ona/ono ma, my mamy, wy macie, oni/one mają). In other verbs, the stem vowel remains the same, so there is very little that needs to be memorized, you can just rely on what you see in the infinitive.

-m,-sz ... -dzą

based on the examples of wiedzieć and dać:

singular		plural
ja	wiem, dam	my	wiemy, dam
ty	wiesz, dasz	wy	wiecie, dacie
on, ona, ono	wie, da	oni, one	wiedzą, dadzą

The second group is very small. It contains the following:

wiedzieć (imperfective, has no perfective equivalent) - watch out for the -dzie- which disappears in the present tense
powiedzieć (perfective of mówić -ę,-isz conjugation) - same, disappearing the -dzie-; btw this one is a derivative of wiedzieć, but due to its very distinct meaning and the fact that it's one of the most frequently used verbs, I thought it was worth including it in a separate point
jeść imperfective, zjeść perfective
dać (perfective of dawać -ę,-esz conjugation)

but keep in mind that the same pattern is also repeated in their derivatives, such as:

powiedzieć: odpowiedzieć to answer, opowiedzieć to tell [a story], zapowiedzieć to announce etc.
dać: dodać to add, oddać to return sth, podać to hand over; to provide, wydać to publish; to issue; to spend [money], sprzedać to sell, przydać się to be useful, zadać to ask; to assign etc.

Which verbs belong to the -m,-sz conjugation?

Disclaimer

There is no concise set of rules that allows you to predict the conjugation type of every Polish verb without fail and solely on the basis of its infinitive form. As always, I encourage you to learn and memorize Polish verbs together with their conjugation pattern.

At the same time, there are several smaller groups of verbs for which prediction is possible and works reasonably well. It's best to treat these patterns as memorization aid: learn a few representative examples and, during exposure to new input, pay attention to familiar-looking patterns.

Besides jeść, basically every verb belonging to the -m,-sz conjugation ends in either -ać or -ieć. But remember, by no means do all verbs ending in -ać or -ieć belong to this conjugation.

Those that do though, usually fall into one of the following patterns (C stands for a consonant):

-aCać
e.g. wymagać, starać się, latać, wracać, pochwalać, wyrażać, etc.
exceptions: the verb lać with prefixes (zalać, nalać), -znawać (przyznawać, uznawać, wyznawać), the verb stawać with prefixes (wystawać, przestawać, dostawać), dawać with prefixes (dodawać, oddawać, podawać, rozdawać), karać with prefixes (ukarać, pokarać, skarać)
-eCać
e.g. czekać, nalewać, rozlewać, uderzać, biegać, przyklejać, strzelać, obrzezać, obiecać, etc.
exceptions: -czesać (przeczesać, uczesać), -epać (klepać, trzepać, telepać), -ebać (grzebać, jebać, kolebać)
-iCać/-yCać
e.g. trzymać, otrzymać, pokazywać, sprzyjać, dotykać, schylać, nazywać, przerywać, zagryzać, zaczynać, etc.
exceptions: the verb lać with prefixes (przylać, wylać), the verb kołysać with prefixes (rozkołysać, zakołysać), -ypać (szczypać, sypać, łypać)

Important: not -ować! Nearly all verbs ending in -ować belong to the -uję,-ujesz pattern (within the -ę,-esz conjugation). The exception is chować and its derivatives (zachować, przechować, wychować...) which conjugate in -m,-sz: chowam, chowasz (historically, this verb is formed from the róot chow- + -ać, rather than from the productive sequence root + -owa- + -ć found in ordinary -ować verbs).