One of three Hebrew words: רֶמֶשׂ remes (H7431), רָמַשׂ ramas (H7430), or שֶׁרֶץ sherets (H8318).

רֶמֶשׂ remes (H7431) comes from a root word that means "to tread" and refers to any rapidly moving animal that crawls or creeps on the ground. רֶמֶשׂ remes is only used in Genesis (cf. Genesis 1:24-26; Genesis 6:7; Genesis 6:20; Genesis 7:14; Genesis 7:23; Genesis 8:17; Genesis 8:19; Genesis 9:3).
רָמַשׂ ramas (H7430) is used throughout the Bible to refer to animals that creep (רָמַשׂ ramas) which the waters brought forth (cf. Genesis 1:21; Psalm 69:34) and living animals that creep (רָמַשׂ ramas) upon the land (cf. Genesis 1:28; Genesis 7:21; Genesis 9:2; Leviticus 11:44; Leviticus 20:25; Deuteronomy 4:18).
שֶׁרֶץ sherets (H8318) means "to swarm," and refers to insects, animals, or small reptiles that teem, swarm, or creep (cf. Genesis 1:20; Genesis 7:21; Genesis 7:21; Leviticus 5:2; Leviticus 11:20; Leviticus 11:21-22; Leviticus 11:23-29; Leviticus 11:31; Leviticus 11:41-44; Deuteronomy 14:19).

These three Hebrew words are all equivalent to the Greek word ἑρπετόν herpeton (G2062) defined as a creeping animal or reptile, as opposed to quadrupeds and birds (cf. Acts 10:12; Acts 11:6; Romans 1:23; James 3:7).
In Leviticus רָמַשׂ ramas and שֶׁרֶץ sherets are both used to describe certain detestable animals forbidden to be eaten:

Leviticus 11:10-12; All that don't have fins and scales in the seas and rivers, all that swarm (שֶׁרֶץ sherets) in the waters, and all the living souls that are in the waters, they are detestable to you, 11 and you will detest them. You will not eat of their flesh, and you will detest their carcasses. 12 Whatever has no fins nor scales in the waters is detestable to you.
Leviticus 11:20-23; All flying that swarm (שֶׁרֶץ sherets) on all fours are detestable to you. 21 Yet you may eat these: of all winged swarmers (שֶׁרֶץ sherets) that go on all fours, which have long, jointed legs for hopping on the land. 22 Even of these you may eat: any kind of locust, any kind of katydid, any kind of cricket, and any kind of grasshopper. 23 But all winged swarmers (שֶׁרֶץ sherets) which have four feet are detestable to you. 24 By these you will become unclean. Whoever touches their carcass will be unclean until the evening. 25 Whoever carries any part of their carcass will wash his clothes [and wash himself in water],^(DSS) and be unclean until the evening.
Leviticus 11:29-31; These are they which are unclean to you among the swarmers (שֶׁרֶץ sherets) that swarm on the land: the weasel, the rat, any kind of great lizard, 30 the gecko, and the monitor lizard, the wall lizard, the skink, and the chameleon. 31 These are they which are unclean to you among all that swarm (שֶׁרֶץ sherets). Whoever touches them when they are dead will be unclean until the evening.
Leviticus 11:41-47; Every swarmer (שֶׁרֶץ sherets) that swarms on the land is detestable. It will not be eaten. 42 Whatever goes on its belly, and whatever goes on all fours, or whatever has many feet, even all swarmers (שֶׁרֶץ sherets) that swarm on the land, them you will not eat; for they are detestable. 43 You will not make your souls detestable with any swarmer (שֶׁרֶץ sherets) that swarms. You will not make yourselves unclean with them, that you should be defiled by them. 44 For I am YHWH your Elohim. Sanctify yourselves therefore, and be holy; for I [YHWH your Elohim]^(LXX) am holy. You will not defile your souls with any kind of swarmer (שֶׁרֶץ sherets) that creeps (רָמַשׂ ramas) on the land. 45 For I am YHWH who brought you up out of the land of Egypt, to be your Elohim. You will therefore be holy, for I am holy. 46 This is the Torah of the animal, and of the bird, and of every living creature that creeps (רָמַשׂ ramas) in the waters, and of every creature that treads on the land, 47 to make a distinction between the unclean and the clean, and between the living thing that may be eaten and the living thing that may not be eaten.' ”

cf. Leviticus 11:44-45