What is the difference between partial and total synonyms?

I am really confused with these terms. In my notes from lexicology lectures, partial synonyms are words which differ in emotional color, valency, style, or grammar. In some cases, I can’t see which of these apply, for example, the following pairs:

• eat/consume
• help/aid
• plenty/many
• former/older
• nest/colonize

Is there another way to define or explain the difference between partial and total synonyms? Or a better list of the possible differences?

There are several assumptions in your question that are not necessarily shared by everyone.

To start with, not everyone recognizes lexicology as a linguistic discipline. While lexicology is quite common in France, Germany, and Eastern European countries (Russia etc.), it doesn't exist in the USA and it is somewhat new in the UK. See a brilliant article by Uriel Weinreich on this, written about sixty years ago.

Secondly, you're using the terms "total synonymy" and "partial synonymy" in your question. The problem is that different linguists understand these terms differently - assuming that they have such concepts in their theories of (English) vocabulary.

As is, your question has no answer.

However, I can tell you what some experts in lexical semantics (aka lexicology) think. For example, John Lyons talks about full synonymy (identical meanings), total synonymy (synonymous in all contexts), and complete synonymy (identical on all levels of meaning). In his theory, he also has "absolute synonyms" (full, total, and complete synonyms), "partial synonyms" (one of the three mentioned above) and "near synonyms" (not identical in meaning).

Alan Cruse uses different terms: absolute synonyms, propositional synonyms, and plesionyms. etc.

It's difficult to find any references on the matter, but the best I could come up with was on an email archive on Corpora-List mailing. Corpora-List is, as the name implies, a mailing list for people interested in linguistic corpora. There was a discussion among linguists about the definition of "corpora", which led to an offshoot discussion about the definition of "synonym". Here was a message (fairly recent, October 2012) written by a professor (Linda Bawcom) whose doctoral thesis was actually about synonyms.

http://mailman.uib.no/public/corpora/2012-October/016364.html

Here's the meat of the message quoted:

I've just used the word 'synonyms'. Has anyone had a problem with that? I would venture to say the majority of you did not because we have a rather collective understanding of that concept among ourselves. Nonetheless, when writing a thesis, you have to define your terms. And here are the problems I faced: some writers very felicitously used 'synonym', others 'near-synonym', still others preferred 'approximate synonym' and then there were writers who preferred rather than define synonym, categorized them by their properties (i.e. partial-synonym, absolute synonym, total synonym) or categorize them by differences (e.g. stylist, expressive). I could go on.

But let's say that most researchers (again agreeing rather collectively) now use the term 'near synonym'. We still have colleagues who are not happy with this term and use their own. I think this rather came about because writers/researchers were not happy with the dictionary definition of synonym (words/phrases that mean (almost) the same-though the Oxford Dictionary gives a very good definition) so they decided to come up with their own term (at least those who felt that synonyms actually exist).

Here's the bottom line (at last). You won't come up with a (new) definition that everyone will agree upon because some will feel that it should be more exacting and others will feel it is too restrictive. And then whose would you use?

So, based on this source at least (and she seems to have done her own research), the terms "partial synonym" and "total synonym" simply don't have agreed-upon meanings in academic or linguistic communities. When used at all, they should really be defined by the researcher/writer using them, and it would not be very helpful to consult an outside source on these definitions, because their definitions might differ in important ways.

Thus, I would follow up with your the person who gives your lexicology lectures to ask them for more specific definitions of the terms as they are using them.