vlookup equivalent for text entries

Is there a function for text entries equivalent to vlookup for data values?

Objective: To have a table of about 20 different measurement units (e.g. mg,
mL, L, lbs, gal, grams, etc.)and adressable corresponding conversion factors.

Vlookup tables require that the lookup values be numbers not text. I need to
be able to assign a numeric value to a cell based on the text content of a
corresponding cell. The number of possible text entries is limited but greater
8, so nested IF statements do not allow for enough options. Also, the initial
letter of the text entries are not always unique, so the CODE function will
not always return a unique numeric code. For example: CODE("milligram") = 109
and CODE("milliliter") = 109