Q: I recently heard two words, pełen and pełny; what is the difference between these two? Can I use them as synonyms?
A: Formally speaking, the male adjective “pełny” (meaning full, complete) and “pełen” (its archaic version) are synonyms in meaning, as they are remnants of a historical dual adjective inflection pattern. However, in most cases it is better to choose a more common version, “pełny”. “Pełen” can be safely used in structures immediately after the verb “jest”, such as: “jestem pełen podziwu” (I am full of admiration), and does not work well with a phrase like “pełen kufel piwa” (a glass full of beer). Other examples of such pairs are “zdrów” and “zdrowy” (healthy), “gotów” or “gotowy” (ready), and they do not occur in the feminine and neuter gender. Some archaic forms survived in the Polish language as phrases, such as “bądź zdrów” (be well, farewell) or “bądź łaskaw” (be as gracious).