How do You concatenate a value to an array that was retrieved through a query in sql?

I have a table named "mkvtable" that establishes a correspondence between individual strings and arrays of strings:

  word   |     mkvword
---------+-----------------
 hello   | {world,friend}
 goodbye | {home,forever}
 hi      | {fellas,ladies}

According to the documentation provided for PostgreSQL, appending a value to an array of values should be a simple matter of using the concatenation operator: "||". However, if, I attempt to add the string there, to the array of strings {fellas,ladies} which correspond to the word hi, nothing appears to happen: SELECT mkvword FROM mkvtable WHERE word = 'hi' || 'there'; PostgresSQL appears to be saying as much: mkvword --------- (0 rows) Since there are no errors thrown, I assume things are syntactically okay. What am I doing wrong? My best guess is that psql is getting upset that I'm trying to access the array by using it's relationship to a value from the adjacent column, but that's just an uneducated guess. Perhaps this sort of query doesn't jell well with the concatenation operator? TL;DR: How do you properly concatenate values to arrays stored in table rows?