I proceed with LENTURA in a similar way to LENTOR. A search in the dictionaries brings 12 results: 11 with the meaning of 'humidity'; 5 of these definitions specify that it is a 'humidity of the soil' and 2 relate this moist with the seasons. Only 1 dictionary turns up this trend and connects LENTURA to warmth, although it must be noted that LENTURA appears as a variant of LENTOR, that is, LENTOR is the defined headword.
Clearly, LENTOR and LENTURA can be regarded as different terms. LENTOR covers both meanings of warmth and humidity whereas LENTURA is much more specific, only related to 'humidity' and more specifically 'humidity of the soil that changes with the seasons'.
A search for LENTURA (with)in the corpus confirms this point. The lemma offers 130 results.
I limit my research to the first 57 entries (up to the year 1979). I must admit that the main reason for doing so is time, that is, I am doing this for the fun of it, but that doesn't mean that checking every single entry is not an arduous task ! ;-) Anyway, the span is wide and representative enough.
The data studied are the most valuable for diachronic analysis, too, as it is the precedent in a chronological succession.
So, here it is. This time I used all the context available from the very beginning. I only reviewed entries to confirm that I did not leave any unchecked and to pick up any particular points when further attention was required.
The first noticeable conclusion is that the semantic field of soil, ground, is absolutely dominant. While LENTOR could be found applied to plants and the sun, LENTURA is predominately present in the earth: 51% of the entries mention LENTURA as inherent to the land whereas this percentage is as low as 7% for LENTOR.
For the main and almost exclusive meaning of 'moist', entries where the semantic-tract is well-explicit (24) reveal (16) 'moist of the soil' as an element inherent of fertile lands, the weather not mentioned. From some examples it can be deduced that the LENTURA disappears with the summer season and under too much heat from the sun. In (4) cases this 'moist' appears to come in from the rain, (1) from the 'dew' and another (1) from the snow. For (1) entry, rather than simply moist, LENTURA appears as a flow or stream.
The range of meanings is reduced and apart from that of 'humidity or moist of the soil' (24) any other semantic tracts are almost anecdotal: only (2) entries are explained as 'warmth'. In (2) cases an idea of +vital-force could be inferred although never as distinctly as for LENTOR.
The number of ambiguous entries is very high (29), although the idea of +moist is almost always present; that is, as it happened for this category in LENTOR, a specific semantic tract could not be clearly inferred. The context is always more easily explained with the idea of LENTURA as 'humidity' or 'fertile land'. For instance the soil is mentioned in (11) entries. Only (5) appear associated to the semantic field of the body: heart, lips, womb, face, body. +Warmth explains the meaning of these sentences, although the idea of +humidity could also be present sometimes. I repeat, the context is not self-explanatory enough, so they are all left as ambiguous, although a more detailed study would bring more significative results.
From these results it looks like LENTURA and LENTOR even if belonging to the same semantic family (it is the same root) differ widely in the proportion of tracts of their semantic field. If we compare them in terms of WARMTH : MOIST : VITAL-FORCE we get 10 : 3.5 : 3.5 for LENTOR and 1 : 12 : 1 for LENTURA.
There is an easy grammatical explanation for this divergence: both terms differ in the suffix -A (LENTUR-A) most often a mark of gender in Romance languages. Not only. In Portuguese this morpheme can also come from an actual distinction in the physical object, measurable in terms of size or extension. Although it is an obvious, regular and intuitive derivation, it usually implies two different entries in dictionaries as the terms derived this way are not synonymous but quite distinct realities: related, yet bearing on well defined semantic boundaries.
Some examples: Portuguese POÇO is a well or a shaft whereas POÇA is a puddle or a pool.
RIO is a river, whereas RIA is an estuary, the tidal entry of the sea within a river.
Even if the divergence looks just grammatical, they are couples each term autonomous, different enough to be considered independent lexical units. It is the same morpheme with an obvious and easily inferred relationship: the appreciation of different measurable qualities in the real object sprout different terms.
They become lexical couples within a paradigmatic relationship, one term feminine, the other masculine; most of the semantic tracts are shared. The significant distinction is quantitative, feminine representing the object with the widest or bigger surface.
This morphological feature could well explain why LENTURA is applied to the soil (wide) whereas LENTOR is more likely to be vapour or dampness (small drops). However, it does not solve out why the proportions of each semantic tract differ so much. This proportional divergence shows a more advanced level of specialization for each term of the couple.
There is some meaningful morphologic information not analysed yet.
Both LENTOR and LENTURA can be explained within the following morphological sequence : ROOT + DERIVATIVE SUFFIX + INFLECTION.
The grammatical suffix or inflection has been already explained. The derivative suffix -/OR/ shows no difficulty: it is a morpheme for a common agent or instrument of action, quite common in European languages.
From here this process of specialization can be understood:
* The root LENT- holds all the common tracts.
* Derivation is made in terms of agent or instrument.
* When a particular agent or instrument becomes too distinct a new term shows up. Here a morpheme that usually indicates a measurable divergence is used.
* The tracts that are more operative remain relevant whereas the others become less evident. Thus, although the idea of LENTURA still can hold +warmth, +vital-force, it is more deeply, almost exclusively associated, with +moist and the earth, the agent or instrument.
To end up, and just as a way to justify the work of so many lexicographers that preceeded this study and made this short article possible: the fact that both terms hold a paradigmatic, all right, grammatical! relationship, almost forces to regard them as close synonyms, although research on the context shows up a high level of specialization.
That's also the reason why, despite too much rain, LENTURA and LENTOR did not split enterely: still waters run deep. Old LENT- remained equivalent to warm and (for instance!!!) fertile HUMOR
. Too subtle, yeah, yet well enough to rise up the SPRING. Weather permitting, of course.