Twice a year, when I visit my in-laws in Poland, I get to dabble in the soft science of linguistics in my futile attempt to learn the Polish language. Few people outside my immediate family can understand me because what I think of as "speaking" others perceive as caveman-like grunts with a Yankee accent.
It's not just me; Polish is, indeed, a difficult language for native English speakers. Why? A handy chart I created shows a side-by-side comparison of various grammatical features of the English and Polish languages with explanations that follow.
Difficult spelling. Spelling Bees exist in both the United States and Poland for a reason: The words are not easy to spell. English has many homophones (e.g., meat/meet/mete), words of foreign origin, silent letters, and arbitrary exceptions, which makes spelling perhaps the language's most difficult feature. Polish isn't plagued by that many problems, but it is still not easy to spell a word given its pronunciation.
Difficult pronunciation. It is not exactly obvious that the correct pronunciation of colonel is KUR-nel or that conceit and receipt rhyme, even though the latter has an extra p in it. Words in Polish, on the other hand, are relatively straightforward to pronounce if given the spelling.
Articles. A, an, and the trip up many native speakers of Slavic languages since articles do not exist in most of them, including Polish and Russian.
Perfective/Imperfective. Both English and Polish are made more complicated by perfective and imperfective verb aspects*. The perfective aspect indicates an action has been completed (e.g., I have gone to the store), while the imperfective aspect indicates an action is ongoing (e.g., I have been going to the store).
And now, the features of the Polish language that make it nearly impossible for a non-native speaker to master.
Complex verb conjugation. Verbs change form -- often dramatically and unrecognizably -- depending on person (1st person - I; 2nd person - you; 3rd person - he/she/it); whether the noun is singular or plural; whether the action is in the past, present, or future; and whether the person speaking (or being spoken about) is a man or a woman. Check out this table, which shows the many, many ways that the Polish verb skakać (to jump) can be conjugated. On the other hand, conjugation of most verbs in English is trivial: Just add -s, -ed, or -ing.
Gendered nouns. Nouns have one of three genders in Polish (masculine, feminine, or neuter), and adjectives that describe those nouns must agree with the gender. The Polish word for table is masculine, lamp is feminine, and beer is neuter. Why? Because.
Multiple plural forms. In English, nouns are either singular or plural, and this is generally indicated by adding an -s. In Polish, there are multiple plural forms and different ways to express plurality depending on the noun. For example, one dog is jeden pies, two dogs is dwa psy, five dogs is pięć psów, and ten dogs is dziesięć psów. Twenty-five dogs uses the psów form, but 32 dogs uses the psy form again. Why? Because. (If there is a pattern to these, no native Polish speaker I've asked knows what it is.)
Noun declension. Declension is probably the most difficult feature of the Polish language. Not only are noun and adjective endings affected by gender and number, but they also change based upon their context in a sentence, known as grammatical case. There are seven different cases in Polish. For instance, table is stół, on the table is na stole, and under the table is pod stołem. English only has a small vestige of this system, which manifests in our substitution of the words I for me, he/she for him/her, and we for us depending on the context.
Conclusion. Many native English speakers are under the false impression that English is a difficult language. It is not. Indeed, as The Economist put it in one of the most memorable essays it ever published, "English is a relatively simple language, absurdly spelled." Polish, on the other hand, seems to me a difficult language designed to intimidate foreigners. At least it's not !Xóõ or Tuyuca.
*Grammar Nazis will point out that English does not have a general imperfective aspect.