I'm a teacher of English as a foreign language, and today I was reviewing some vocabulary from a book with my students. We found "irksome" and "pestering" to refer to something that is annoying. A student asked if there was a way to know when to use "irksome" and when is better to use "pestering". So, it occurred to me that maybe there is a way to know what word is the best fit to a given context, maybe a dictionary or another type of resource.
You use irksome of something that irks you.
You use pestering of something that pesters you.
Both irk and pester refer to some irritation of their objects
(which must be human or at least capable of emotion), but they have different connotations.
Pester refers to repeated episodes of being irritated (usually by something or someone).
Irk simply means being irritated (ditto), with no reference to history or repetition.
There are several approaches:
A. Since the question "What word is the best fit to a given context?" is a question about collocation, you could use a collocation dictionary, such as the LTP Dictionary of Selected Collocations.
If your context or starting point is a noun such as problem, the dictionary entry will give you a list of the verbs and adjectives that collocate with it. Similarly, starting with an adjective such as opposed you are given a list of collocate adverbs (adamantly, bitterly, vehemently, implacably ...).
B: Use an online concordancer such as the COCA which allows you to do a KWIC (Keyword in context) search. This will return examples of the word in numerous authentic contexts. You can scan the results list to see if there are contexts that match yours. (You will note, for example, that pestering is much more common in a verb phrase than as an adjective.)
C: Search Google for the phrase containing the word you are interested in. So if you want to know which is the more common collocate of problem (irksome or pestering), enter each phrase, compare the number of hits and scan the results for the phrase in its context. (Irksome is about three times more common as a collocate of problem than pestering.)
D: Do a Google Books Ngram comparison. (Irksome problem is quite common, but there is no occurrence of pestering problem.)
E: Do a back translation into the mother tongue. So, for example, pestering translates as drangsalierend; plagend; piesackend in German and irksome as ärgerlich; lästig. This will often help you to see which one better fits your context.
In Collins Thesaurus, 'Irksome' has the following synonyms:aggravating, annoying, boring, bothersome,burdensome,disagreeable,exasperating,tedious,tiresome,troublesome,trying,uninteresting,unwelcome,vexatious,vexing,wearisome.
'Pester' has the following: badger, bedevil,bother, bug, chivvy, disturb,fret, get at (inf), harass, harry, hassle,irk,nag,pick on,plague,ride,torment, worry.
So irk is a synonym of pester but not vice-versa.
Choice of words in some ways is like choosing clothes to wear. there are no hard and fast rules, you just need to find something which seems right in the context. And that can depend on how words are accepted and used in the environment you are working with.
I teach upper primary school and this is a huge problem, because their experience of English language is often small and narrow and so have not used the less commonly heard synonyms, therefore they do not come with associated connotations. The only way I have found so far to help with this (because it ruins a good story to say that the china vase was bankrupt) is to subscribe to Visual Thesaurus. It gives the visual representation of the connections between words in a way that groups synonyms together, whilst providing definitions of the word as used as noun, verb, adjective (if applicable). This helps, if you can train your pupils to use it. Having just read your other responses though, I just tried COCA and it does the same thing and provides interesting teaching avenues (although at an often high level of understanding).