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I can't seem to find a GOOD definition of these two words relative to biology.
Also, what is the meaning and history of the word morph-.
And, how does in differ from mutant?

"Morphology" is approximately equivalent to external anatomy.
Morphological is a the adjective form.
"morph" is often used in the herpetocultural community for any color variant, natural or artficial. It is probably derived from the scientific term Polymorphic, which is applied to any group with different phenotypes, especially color variants.
"Mutant" is any animal with a different phenotype than its parents, but is most often used in decribing abnormal variants.

>>I can't seem to find a GOOD definition of these two words relative to biology.
>> Also, what is the meaning and history of the word morph-.
>> And, how does in differ from mutant?

The root 'morph(o)-' is from Greek 'morphos' meaning shape or form ('forma' in Latin has the same meaning and may be cognate - i.e. the same word in the ancestral Indo-European - though the inferred switcheroo of consonants would be irregular)

'Morphology' refers to the study of shape or form, and in biology means the description and comparison of the shape and arrangement of body structures both internal and external, macroscopic ('gross morphology') and microscopic. Internal morphology can also be called 'anatomy', which literally refers to the act of 'cutting up' specimens for study. Look up the list of titles in any issue of 'Journal of Morphology' to see what (biological) morphologists do.

'Morphological' is just the regular adjectival form of the noun, which can be used in all the same senses and contexts as the noun (e.g. referring to 'form' in linguistics, musicology, geology etc. as well as biology).

By extension, we refer to the 'morphology' of an animal as the set of observable features of shape, colour, size, number of repeated parts etc. (i.e. if we say that the subject matter of morphology is morphology, the senses of the word are distinct and the statement is true)

I'm not sure of the actual history of 'morph' as used by fanciers of inbred domesticates, but I suspect it is a back-formation from the taxonomic or population-genetic use of 'monomorphic', 'dimorphic', 'polymorphic' etc. in reference to having one or more distinct modes of variation within a natural population.

'Mutant' and 'mutation' are terms of early C20 genetics that have been widely misunderstood and misapplied by nearly all kinds of persons. In Latin, 'mutare' just means to change, and 'mutation' (in genetics) means a change of any kind in the somatic or germ-line genetic material of a cell or individual. A 'mutant' is an individual (or cell line) carrying such a (recent) change; a 'mutant allele' is a copy of the gene with the change (as opposed to the 'wild type' allele). There may or may not be any phenotypic (observable) effect of any particular mutation in organisms carrying either single or double copies, i.e. the 'mutant' phenotype may not be distinguishable from the wild type. Or it may be different enough to be lethal in the egg, observable but selectively neutral (in the wild), or beneficial for survival or reproduction.

As well as referring to a single event and its product, we can refer to 'mutation' as the ongoing process of changes in genes as far as they are initiated at the molecular level. Mutation provides the raw material for natural selection (this is the core of the 'neo-Darwinian' synthesis in evolutionary theory; synthesis is Greek for 'putting together', in this case of natural selection with genetics), together producing change in populations of genes and genomes (and morphologies) over short and long time scales. World without end. Amen.

As for how they're used in the trade, you'll have to wait for an answer from a breeder. It can't all be about brand names and spin; possibly the purpose is to distinguish naturally occurring, viable 'morphs' from variants not observed, or not viable, in wild populations (albinos, dicephalics, ...)
-----
John D. Scanlon
Riversleigh Fossil Centre
Outback at Isa
Mount Isa, Queensland, Australia
riversleigh@outbackatisa.com.au

Initially the term "morph" was used pretty much as biologists use it, to mean one of the distinctive forms of a polymorphic species. For example, the california kingsnake occurs in two pattern morphs -- striped and banded. Then, as you put it, the "inbred mutant" market took off, and people who probably never knew what morph meant anyway started applying it to any color or pattern variation, naturally occuring or not. (I guess it's all naturally occuring, strictly speaking, but you get my meaning).

> For example, the california kingsnake occurs in two pattern morphs -- striped and banded.

There are more than 2 morphs found in the wild. There is the black belly morph, the Long Beach morph, the yumensis morph (with narrow light bands), for example. Some poeple still maintain that yumensis is a valid subspecies, and not an intergrade between Lampropeltis getulus californiae and L. g. nigritus.

Reference
Zweifel, R. G. 1981. Color pattern morphs of the kingsnake (Lampropeltis getulus) in southern California: distribution and evolutionary status. Bulletin Southern California Academy Sciences 80(2): 70-81.