Tapilula has an inventory of private verbs: verbs whose meaning is dependent entirely on the noun class of the agent and patient of the verb.
- 1 Private verbs
- 1.1 Noun classes for agents
- 1.2 Noun classes for patients
- 1.3 Interaction of agents and patients
- 2 Notes
All private verbs consist of a single syllable, always on the high tone (spelled `).
Noun classes for agents
Tapilula had an animacy hierarchy, such that only animate nouns could be the agent of any verb. Intransitive verbs are not considered to distinguish agent and patient in this language. Note also that there was no case marking in Tapilula; this was innovated independently in the daughter languages, and of those, only the genitive comes from the same morpheme in both Andanese and Gold — the infix -ə̀h-.
Parent noun class I: Humans and other sapient beings
Humans are at the top of the animacy hierarchy in Tapilula and in all of its descendants, although most of the descendants divide humans into higher and lower forms. Some animals are also included in this class, and were included from the very beginning of the development of the system.
The Human superclass is subdivided by gender and age, as well as for species in the case of the non-humans who are grouped with them as fellow sapients. The superclass includes:
- Adult female (fi-) ; accusative is mi-
- Adult male (tə-); accusative is hə-
- Young female, maiden (ni-); accusative is ŋi-
- Children, babies; birds; fish; (nu-); accusative is ŋu-??
- Epicene; pregnant women (pu-); accusative is bu-
- Crustaceans (pe-); accusative is be-
- Ducklike birds (ni-); accusative is ŋi-
Note that birds, fish, and children are all in the same category, marked by nu-. This is considered to be the categorical marker of the human parent class, but among humans, children are the only group who are not marked with an additional gender marker which supplants the species marker nu-. Buildings are also included, but can only appear as agents when serving metonymically for humans who occupy them.
The prefixes for some animals, such as crustaceans, are included here for completion's sake but are actually only used when padded with the "fish" prefix nu-, which is used because crustaceans are found near fish.
Parent noun class II: Land animals
Large land animals that do not have gender distinctions are carried here. Since this is a habitat-based classification, seabirds such as penguins are not included, and neither are any other birds.
- Snakes (ŋe-)
- Frogs and amphibians (hə-)
- Turtles (li-); accusative is yi-
- Rabbits (tə-)
- Mice and rodents (la-); accusative is yi-
- Flying insects (ka-); accusative is ha-
- Cats (ḳe-); accusative is bə-
- Sheep; goats (pa-); accusative is ba-
- Worms (fi-); accusative is mi-
- Ants and other crawling insects (po-); accusative is bo-
- All other large land animals (Andanese la-; possibly composite); accusative is ya-
Meat is classified here, as all meat comes from animals.
Noun classes for patients
All agents can also be patients, so the numbering of the noun classes for patients starts where the agents left off.
Parent noun class III: Inalienable possessions
Inalienable possessions can be elevated to full animate status by various means.
- Unorganized nouns (no classifier prefix); family relations are found here rather than taking the fixed prefixes one would expect for their gender.
- Edible body parts (i-)
- Inedible body parts (mi-)
- Blood, bodily humors (do-)
- Claws and other hard body parts (hu-); sometimes used for thorns and plant parts; also see nə- below for manmade sharp objects
- Teeth (ti-)
- Bones (ḳo-)
- Female genitals (ŋi-)
Parent noun class IV(?): Manmade objects
- Handheld objects (yo-)
- Claws and sharp objects (nə-)
- Arrows and similar weapons (tu-)
- Whips and similar objects (a-)
- Some other handheld objects (gi-)
- Wheels (ḳe-)
- Furniture (o-)
- Non-weaponous handheld tools (ḳu-)
- Other handheld objects (hə-)
Parent noun class V(?): Plants and other parts of nature
- Trees (ka-)
- Trees (hi-)
- Trees (pu-)
- Flower blossoms (ti-)
- Succulent fruit (tu-)
- Grass; clover; small plants (du-)
- Some very tall grasses (ma-)
- Another type of grass (pe-)
- Grass in general (wo-)
- Other fruits (ŋu-)
- Coral (hə-)
The Andanese ya- noun class, which is highly composite, is secondary and thus not represented here. It corresponds mostly to originally disyllabic full words in which the original two vowels were /i/ and /a/. For example, Tapilula ḳèga became Late Andanese ya-, no longer meaningful as a standalone word.
Newly discovered trees are placed into the ka- group regardless of their physical appearance.
Many fruits have very short names, such as bə̀ "apple", hì "cranberry", and wì "cantaloupe, melon", and are used as if they were classifiers. Names of trees are also often short; bà "maple" and nà "spruce" are examples.
Parent noun class VI: Mass nouns
These nouns cannot take the plural prefix u-.
- Water; weather (pi-)
- Wind, air (hu-)
- Alcohol, soap, and other formulas (me-)
Parent noun class VII: Places and invincible passives
Unlike all other nouns, even animates, members of this class cannot be either an agent or a patient of any verb. That is, when one sees the sun in the sky, the sun is not affected by this, and therefore Tapilula can only use an intransitive verb. Thus, these nouns cannot take the accusative infix -i-.
- NOTE, does this even matter, though? None of the other nouns in classes III-VII can be agents either, so accusative is going to be their default class anyway.
- Celestial objects (fu-)
- Oceanographic features (fo-)
- Hills and land masses (o-)
- Buildings (nu-)
- Open places (ə-) 
- [Morpheme found in "love" and "sleep"] (fə-)
- Kingdom, empire (me-)
- [Possibly found in "spirit"] (e-)
These classes may need to be separated. The locative /ŋə/ is omitted on all VII nouns.
Interaction of agents and patients
Tapilula's private verbs carry different meanings for each combination of agent and patient noun class. Since there are two noun classes that can act as agents and six that can act as patients, there are twelve categories of private verbs.
- ... possibly na-, saying that mi- was a corruption of the word for breast
- Not in dictionary; uses Andanese reflex. Perhaps an attempt to relate to Khulls lĕ, even though this could only have come from nu-, the same as the child classifier.
- Depends on the primeval nu- of the bird class being identical with the first syllable of the primeval word for child, which was later extended to all humans.
- or pə-
- ta- also abailable
- implied in pŏle "ant", since lè = ant already
- If la- is original, mouse/rodent merges into this.
- Tentative; really this is just a passive prefix that later becomes the marker for edible body parts when combined with the word for "eat".
- This is actually the word for hand itself.
- see həhìki "key"
- cognate to andanese ni-; the initial vowel was lost.