This is the first word of the article: לשם.
Of course, opal will not work.
It is not difficult to see that this is likely to be the result from the merging of the common noun שם, which means noun and the preposition ל, which means to. If so, we'd got "to noun".
Look at word number 519.
But we have here a literal meaning of the word. Now, a good translator searches for a sound meaning.
Bien sûr in French means "well sure", but this is a literal translation, a slave translation. What then? "Quite true" is the good English translation of these two French words taken as a whole, coming together.
A further searching in your dictionary will show that לשם means also "concerning..."
Remark how this meaning is different from the meaning of word number 161 even if they are formally the same.