A list of the top 100 misspelled words in English can be viewed at the websites of Oxford Dictionaries and the O. G. Wiederstein Elementary School in Texas. Examples include "beautiful," "February," "surprise," "received" and "friend."
Each of these words is subject to a particular rule of spelling, or else has an unusual and misleading sound. "Friend," for example, is subject to the "i before e" rule, which many people forget. "Received," on the other hand, defies this rule with its own amendment: "i before e except after c." With "surprise," perhaps owing to its everyday pronunciation, many people forget to include the letter R and spell the word simply as "suprise" instead.
A longer and more comprehensive list of commonly misspelled words can be found at the ESL Desk website. These are words that people who are learning English as a second language, especially, might have problems with.
Many of these words, such as "gauge," "island," "knowledge," "mosquito" and "Wednesday" are pronounced differently to the way that they are spelled. Mosquito, in particular, is fairly unique among English pronunciations of a Q and U in combination. As a plural it might also be problematic, since the final S is preceded by an E.