(1) Vowel letters of Hindi Alphabets - a, aa, i, ee, u, oo etc.

(2) Devee. Maaatrikaa is a group of Hindu goddesses who are always depicted together. Since they are usually depicted as a heptad, they are called Sapt Maatrikaa (seven mothers):
--Brahmaanee - is the Shakti (power) of the creator god Brahma. Fixes: Pride.
--Vaishnavee - is the power of the preserver-god Vishnu. Fixes: Being too Polite
--Maaheshwaree - is the power of god Shiv. Fixes: Anger
--Indraanee - is the power of the Indra. Fixes: Fault-finding
--Kaumaaree - is the power of Kumara (Kartikeya or Skanda), the god of war. Fixes: Denial
--Varaahee - is described as the power of the boar-headed form of Vishnu or Yama. Fixes: Envy
--Chaamundaa or Narasinhee - is identified with Kali. Fixes: Gossip

However, they may sometimes be eight (eight mothers). Whereas in South India, Sapt Maatrika worship is prevalent, the Asht Maatrikaa are venerated in Nepal.

Naarad Puraan, 1/23 describes 16 Maatrikaa, their names are - (1) Gauree,  (2) Padmaa,  (3) Shachee,  (4) Medhaa,  (5) Saavitree,  (6) Vijayaa,  (7) Jayaa,  (8) Devsenaa,  (9) Swadhaa,  (10) Swaahaa,  (11) Maatrikaayen,  (12) Vaidhriti,  (13) Dhriti,  (14) Pushti,  (15) Hrishti, and  (16) Tushti. They should be worshipped before worshipping planets.

One must worship them at the time of increase in one's family, for example at the time of birth, marriage, opening a new business etc.

Two Kinds of Maatrikaa
There are two kinds of Maatrikaa -
(1) the beneficent 8 Shakti - (1) Brahmaanee, (2) Kaarttikeyee, (3) Varaahee, (4) Vaishnavee, (5) Maaheshwaree, (6) Maahendree, (7) Aindree, and (8) Yamee; and

The Yoginee Tantra (Eighth Patal) gives an account of the origin of the Daakinee Maatrikaa. At the dissolution, when nothing was left in Shiv, but the five elements, he asked his Shakti to find him a place for them, his own creation having been destroyed. Shakti said that the Creation was hers, and not his, for without her Shiv was only a Shava (corpse). At this Shiv went away in anger, and going westward he created a demon of huge form out of the ashes of his body. He then returned to Shakti and took her with him to he demon. The demon, on seeing Shakti, was overcome by lust for her and begged of her to save his life by the gratification of his desire. Shakti assented if he could defeat her in battle. It was then that Shakti threw out from herself the terrible Maatrikaa who are those referred to as Daakinee Maatrikaa.
[From Tantra of the Great Libration (Maha Nirvan Tantra).  by Arthur Avalon. p 27]

Yoginee is one of the Maatrikaa - attendants of Kaalee.